Breast cancer is the most common cancer among women worldwide, and there are several possible methods for screening.
If facilities are available, screening by mammography alone, with or without physical examination of the breasts, plus follow-up of individuals with positive or suspicious findings, will reduce mortality from breast cancer by up to one-third among women aged 50–69 years (IARC, In press).
Much of the benefit is obtained by screening once every 2–3 years. There is limited evidence for its effectiveness for women 40–49 years of age (IARC, In press)(see Figure 5.2). The Health Insurance Plan (HIP) study, which used physical examinations by surgeons, suggested benefits in younger women only after they had reached their fifties (Shapiro, 1997). A cohort study in Finland suggested breast self-examination to be of benefit at all ages (Gastrin et al., 1994), as did a case-control study in Canada (Harvey et al., 1997).
However, observational studies of these latter types cannot exclude selection bias and may overestimate benefit. A randomized trial of breast self-examination in China has not found any evidence of reduction in breast cancer mortality after long-term follow-up (IARC, In press). This suggests that a programme to encourage breast self-examination alone would not reduce mortality from breast cancer. Women should, however, be encouraged to seek medical advice immediately if they detect any change in a breast that suggests breast cancer.
Unfortunately, mammography is an expensive test that requires great care and expertise both to perform and in the interpretation of results. It is therefore currently not a viable option for many countries. Although there is inadequate evidence that physical examination of the breasts as a single screening modality reduces mortality from breast cancer (IARC, In press), there are indications that good clinical breast examinations by specially trained health workers could have an important role. These come from the HIP study where mammography detected a low proportion of breast cancers, especially in women under the age of 50 (Shapiro, 1997), yet breast cancer mortality was reduced. Similarly, in the Canadian National Breast Screening Study, where the addition of mammography to such examinations in women aged 50–59 did not result in a reduction in breast cancer mortality (Miller et al., 2000a).
Given the present level of evidence, the national cancer control programme should not recommend screening by breast self-examination and physical examinations of the breast. Rather, the programme should encourage early diagnosis of breast cancer, especially for women aged 40-69 years who are attending primary health care centres or hospitals for other reasons, by offering clinical breast examinations to those concerned about their breasts and promoting awareness in the community. If mammography is available, the top priority is to use it for diagnosis, especially for women who have detected an abnormality by self-examination. It should be borne in mind, however, that cancer may be present even if the mammogram is negative. Mammography should not be introduced for screening unless the resources are available to ensure effective and reliable screening of at least 70% of the target age group, that is, women over the age of 50 years.
In determining the relative priorities for different screening programmes, it is important to recognize that breast cancer screening is intrinsically less effective than cytological screening for cervical cancer. As a rough guide, screening will produce an equivalent reduction in numbers of deaths in the two conditions only if, in the absence of screening, breast cancer mortality is three times that of cervical cancer in the age groups concerned.
Conclusions
1. What clinically significant alterations in metabolism occur in animals with cancer cachexia? Dogs and cats with cancer have significant alterations in carbohydrate, lipid and protein metabolism that can result in cancer cachexia. These alterations in metabolism have the potential to decrease quality of life, reduce response to therapy and shorten survival times.
2. How can knowledge about the metabolic alterations in metabolism change the way you use nutrition to treat your cancer patients? While the ideal anticancer diet is not known, research to date would suggest that any nutritional support is better than none. Normal feeding practices should begin early before evidence of cachexia are noted, and plans should be designed to support the patient when voluntary feeding is not optimum. In addition, the following guidelines may be considered early for each patient:
a. Arm clients with appropriate information, dietary plans and appetite stimulants such as cyproheptadine and megesterol acetate from the very beginning. The goal is to prevent anorexia and weight loss from ever happening.
b. Consider foods that are highly bioavailable, easily digested, and highly palatable with a good smell and taste
c. Consider foods that are relatively low in simple carbohydrates, moderate amounts of good quality sources of proteins and soluble and insoluble fiber, and moderate amounts of fats; fats of the n-3 fatty acid series may be effective in reducing or eliminating some of the metabolic alterations associated with cancer cachexia. Antioxidants are essential whenever n-3 fatty acids are used. Hills prescription diet nd is one good example.
d. Enhanced quantities of arginine, cystine and glutamine may be of value in maintaining a more normal immune, hematologic and gastrointestinal tract.
e. Fiber, both soluble and insoluble, is essential to maintain normal bowel health. A diet with adequate amounts of fiber is essential to prevent or to treat various problems of the gastrointestinal tract.
3. Does surgery, chemotherapy or cancer increase or decrease the energy needs and the amount you should feed your patient? Each patient should be assessed as an individual and the nutritional profile, including the amount to be fed should be prescribed for each animal on a daily basis based on reassessments. As a general rule, with the exception of septic animals, dogs and cats with cancer, critical care illnesses, or that are recovering from surgery do not have energy needs that exceed those of normal animals. A formula that approximates the need for many animals with cancer in a resting state is as follows: 1.1[30(wt in kg) + 70]= kcals required per day.
4. Are there any data on the efficacy of the nutrients my clients constantly ask me about: vitamins, minerals, proteases, enzymes, garlic, tea and shark cartilage? What nutrients should you feed your cancer patient? Data exist demonstrating that many antioxidants, minerals, proteases, garlic, enzymes, and tea all have some potential for reducing the risk of cancer, or the growth and metastases of established malignant diseases. Research must be done to establish ideal dosages, and optimum applications of these nutrients. The lay press and word of mouth can bypass the presence of any research data demonstrating efficacy as it has for shark cartilage. To date, little if any data exist demonstrating that shark cartilage is effective for treating spontaneously occurring cancer in an outbred species. Despite this lack of proof, the public does believe that shark cartilage does have some efficacy.
5. What are the indications for intervening aggressively with appetite stimulants, tube feeding or total parenteral feeding for your cancer patients? For maximum benefit, intervention should begin early in the course of the disease. The owner must have a clear plan for dietary intervention beginning first with the choice of nutrients, followed by appetite stimulants, and then on to feeding tubes for those patients that cannot or will not support themselves.
2. How can knowledge about the metabolic alterations in metabolism change the way you use nutrition to treat your cancer patients? While the ideal anticancer diet is not known, research to date would suggest that any nutritional support is better than none. Normal feeding practices should begin early before evidence of cachexia are noted, and plans should be designed to support the patient when voluntary feeding is not optimum. In addition, the following guidelines may be considered early for each patient:
a. Arm clients with appropriate information, dietary plans and appetite stimulants such as cyproheptadine and megesterol acetate from the very beginning. The goal is to prevent anorexia and weight loss from ever happening.
b. Consider foods that are highly bioavailable, easily digested, and highly palatable with a good smell and taste
c. Consider foods that are relatively low in simple carbohydrates, moderate amounts of good quality sources of proteins and soluble and insoluble fiber, and moderate amounts of fats; fats of the n-3 fatty acid series may be effective in reducing or eliminating some of the metabolic alterations associated with cancer cachexia. Antioxidants are essential whenever n-3 fatty acids are used. Hills prescription diet nd is one good example.
d. Enhanced quantities of arginine, cystine and glutamine may be of value in maintaining a more normal immune, hematologic and gastrointestinal tract.
e. Fiber, both soluble and insoluble, is essential to maintain normal bowel health. A diet with adequate amounts of fiber is essential to prevent or to treat various problems of the gastrointestinal tract.
3. Does surgery, chemotherapy or cancer increase or decrease the energy needs and the amount you should feed your patient? Each patient should be assessed as an individual and the nutritional profile, including the amount to be fed should be prescribed for each animal on a daily basis based on reassessments. As a general rule, with the exception of septic animals, dogs and cats with cancer, critical care illnesses, or that are recovering from surgery do not have energy needs that exceed those of normal animals. A formula that approximates the need for many animals with cancer in a resting state is as follows: 1.1[30(wt in kg) + 70]= kcals required per day.
4. Are there any data on the efficacy of the nutrients my clients constantly ask me about: vitamins, minerals, proteases, enzymes, garlic, tea and shark cartilage? What nutrients should you feed your cancer patient? Data exist demonstrating that many antioxidants, minerals, proteases, garlic, enzymes, and tea all have some potential for reducing the risk of cancer, or the growth and metastases of established malignant diseases. Research must be done to establish ideal dosages, and optimum applications of these nutrients. The lay press and word of mouth can bypass the presence of any research data demonstrating efficacy as it has for shark cartilage. To date, little if any data exist demonstrating that shark cartilage is effective for treating spontaneously occurring cancer in an outbred species. Despite this lack of proof, the public does believe that shark cartilage does have some efficacy.
5. What are the indications for intervening aggressively with appetite stimulants, tube feeding or total parenteral feeding for your cancer patients? For maximum benefit, intervention should begin early in the course of the disease. The owner must have a clear plan for dietary intervention beginning first with the choice of nutrients, followed by appetite stimulants, and then on to feeding tubes for those patients that cannot or will not support themselves.
Enteral Feeding Methods
The type of nutrients to be used depends largely on the enteral tube that is used and on the status of the patient. 1-3,5,83,87,88 The big question is: what should you feed the cancer patient? The easy answer is, whatever the pet will eat, however, specific therapy is preferred. Blended canned pet foods may be adequate for feeding by esophagostomy and gastrostomy tubes. Whenever possible, consider diets that are relatively low in simple carbohydrates, easily digestible, and that have appropriate soluble and insoluble sources of fiber. The later can be accomplished by adding psyllium to a canned maintenance pet food diet or by using a weight maintaining diet such as Hills Prescription Diet W/D. Because the later has restricted calories, an increased volume of feeding may be needed. Human enteral feeding products are easily administered though nasogastric and jejunostomy tubes (e.g., Impact, Osmolite HN, Jevity), however, veterinary enteral products are now available that are specifically tailored for the nutritional needs of animals, especially cats (e.g, Clinicare). In any case, feeding usually is not started until 24 hours after the tube is placed except for pets with an esophagostomy tube. Once feeding is started, the amount of nutrients is gradually increased over several days and is administered frequently in small amounts, which allows the animal to adapt to this method of feeding. Continuous feeding may reduce the risk of vomiting caused by overloading the GI tract. Regardless, the tube should be aspirated 3 to 4 times a day to ensure there is not excessive residual volume in the GI tract. The tube should be flushed periodically with warm water to prevent clogging.
Enteral Nutrition
Enteral dietary therapy has been shown to be a practical, cost-effective, physiologic, and safe modality that may abate or eliminate cancer cachexia, decrease complications from therapy and actually improve response to therapy. Several studies have failed to document the possibility of increasing tumor growth by enhancing the nutritional status of the host. 83-88 The dogma is that mature dogs and cats with a functional gastrointestinal tract that have a history of inadequate nutritional intake for 3-7 days or have lost at least 10% of their body weight over a 1-2 week period of time are candidates for enteral nutritional therapy. There is no question that this philosophy is short sighted. Nutritional intervention must begin earlier than these guidelines suggest. The key is to prevent problems before they occur.
As a general rule, mature dogs and cats with cancer with functional GI tracts that require nutritional support should have some form of enteral feeding: If the gut works, use it!!! The first step is to enhance appetite. The owner should be given a short term and long range plan for the nutritional support of their pet. This plan allows the veterinary health care team and the owner to have a sequential plan for maintaining nutritional support by first enhancing appetite, second, using tube support in appropriate cases, and third, considering more advanced measures such as total parenteral nutrition for serious problems. The first step, enhancing appetite, begins with the basics: warming the food to just below body temperature; providing a selection of palatable, aromatic foods; and providing comfortable, stress-free surroundings. When these simple procedures fail, such chemical stimulants as benzodiazepine derivatives (e.g., diazepam and oxazepam) and antiserotonin agents (cyproheptadine and pizotifen) can be used. Cyproheptadine (2-4 mg daily or twice daily PO) generally is effective in stimulating appetite in cats, as are megestrol acetate (2.5 mg daily for 4 days, then every 2-3 days thereafter). These drugs can be used concurrently for maximal stimulation of the appetite. Diazepam (0.05-0.5 mg/kg IV) is great for short term therapy in the hospital, but is often not adequate for home therapy. Dogs and cats may have improved appetite when metoclopramide is given orally to decrease nausea associated with chemotherapy or surgery. When all the aforementioned fails, enteral nutritional support via nasogastric, esophagostomy, gastrostomy or jejunostomy tube feeding, designed to deliver nutrients to the GI tract should be considered because it is practical, cost-effective, physiologic, and safe.1-4
As a general rule, mature dogs and cats with cancer with functional GI tracts that require nutritional support should have some form of enteral feeding: If the gut works, use it!!! The first step is to enhance appetite. The owner should be given a short term and long range plan for the nutritional support of their pet. This plan allows the veterinary health care team and the owner to have a sequential plan for maintaining nutritional support by first enhancing appetite, second, using tube support in appropriate cases, and third, considering more advanced measures such as total parenteral nutrition for serious problems. The first step, enhancing appetite, begins with the basics: warming the food to just below body temperature; providing a selection of palatable, aromatic foods; and providing comfortable, stress-free surroundings. When these simple procedures fail, such chemical stimulants as benzodiazepine derivatives (e.g., diazepam and oxazepam) and antiserotonin agents (cyproheptadine and pizotifen) can be used. Cyproheptadine (2-4 mg daily or twice daily PO) generally is effective in stimulating appetite in cats, as are megestrol acetate (2.5 mg daily for 4 days, then every 2-3 days thereafter). These drugs can be used concurrently for maximal stimulation of the appetite. Diazepam (0.05-0.5 mg/kg IV) is great for short term therapy in the hospital, but is often not adequate for home therapy. Dogs and cats may have improved appetite when metoclopramide is given orally to decrease nausea associated with chemotherapy or surgery. When all the aforementioned fails, enteral nutritional support via nasogastric, esophagostomy, gastrostomy or jejunostomy tube feeding, designed to deliver nutrients to the GI tract should be considered because it is practical, cost-effective, physiologic, and safe.1-4
Do Dogs with Cancer have Increased Energy Expenditure
Studies were initiated to determine if animals with cancer have altered energy expenditure and to determine if elimination of cancer with chemotherapy or surgery alters energy expenditure.80,81 In the first study80, indirect calorimetry was performed on dogs with lymphoma that were randomized into a blind study and fed isocaloric amounts of either a high fat diet, or a high carbohydrate diet before and after chemotherapy.89 Surprisingly, during the initial evaluation period, resting energy expenditure was significantly lower than tumor-free controls. Six weeks after the start of the study, EE was significantly lower in both groups of dogs with lymphoma when compared to the controls and the pretreatment values from the dogs with lymphoma. Dogs fed the diet that is relatively high in fat maintained a more normal energy expenditure than dogs fed a diet relatively high in carbohydrates.
Another study was undertaken to determine energy expenditure of client-owned dogs with nonhematopoietic malignancies in an apparently resting state before and after each tumor was surgically excised.81 Surgical removal of the tumor did not significantly alter any parameter when all dogs were assessed as a single group, or when these animals were subdivided into the following groups: carcinomas and sarcomas, osteosarcomas and mammary. The values obtained prior to any treatment from the dogs in any group were not significantly different from controls. These data suggest that energy expenditure, and presumably caloric requirements of dogs with non-hematopoietic malignancies, are not different from those obtained from healthy client-owned dogs. Furthermore, these parameters do not change significantly when the tumor is removed surgically and the patient is re-assessed after 4-6 weeks.
Another study was undertaken to determine energy expenditure of client-owned dogs with nonhematopoietic malignancies in an apparently resting state before and after each tumor was surgically excised.81 Surgical removal of the tumor did not significantly alter any parameter when all dogs were assessed as a single group, or when these animals were subdivided into the following groups: carcinomas and sarcomas, osteosarcomas and mammary. The values obtained prior to any treatment from the dogs in any group were not significantly different from controls. These data suggest that energy expenditure, and presumably caloric requirements of dogs with non-hematopoietic malignancies, are not different from those obtained from healthy client-owned dogs. Furthermore, these parameters do not change significantly when the tumor is removed surgically and the patient is re-assessed after 4-6 weeks.
Carbohydrate, Protein, Fat and Fiber, What Do I Feed My Dog with Cancer
The data noted above suggest that a diet relatively low in simple carbohydrates, with moderate amounts of highly bioavailable proteins as well as soluble and insoluble fiber, and moderate amounts of polyunsaturated fatty acids of the n-3 series may be of value to the cancer patient. Research is needed to address the issue of optimum quantities of carbohydrates, proteins and fats, especially n-3 fatty acids. In addition, the ideal ratio of n-3 fatty acids to n-6 fatty acids also remains an unknown. The ideal diet is made of much more than carbohydrates, proteins and fats. A brief discussion about some of what is known about vitamins, minerals and other ingredients is listed below.
Fiber
Soluble and insoluble fiber are both important to prevent cancer and to enhance bowel function. This can be especially important for the cancer patient that may undergo chemotherapy, radiation therapy and surgery. Fiber is important not only to treat disorders of the gastrointestinal tract, but also to prevent concurrent diseases such as clostridial colitis. Therefore, a diet with adequate amounts of soluble and insoluble fiber may be indicated for many dogs and cats with cancer.
Lipid Metabolism
Fat loss accounts for the majority of weight loss occurring in cancer cachexia. Therefore, it is not surprising that human beings and animals with cancer have dramatic abnormalities in lipid metabolism.33-37 The decreased lipogenesis and increased lipolysis observed in humans and rodents with cancer cachexia result in increased levels of free fatty acids, very low density lipoproteins, triglycerides, plasma lipoproteins, and hormone dependent lipoprotein lipase activity, while levels of endothelial derived lipoprotein lipase decrease.34 Recently lipid profiles in dogs with a lymphoma were studied.35 It was determined that many of the alterations seen in other species with cancer were also present in dogs. These abnormalities did not normalize when clinical remission is obtained. The clinical significance of these abnormal lipid profiles in dogs with lymphoma is not known, however, abnormalities in lipid metabolism have been linked to a number of clinical problems including immunosuppression which correlates with decreased survival in affected humans.16,32,34
The clinical impact of the abnormalities in lipid metabolism may be lessened with dietary therapy. In contrast to carbohydrates and proteins, some tumor cells have difficulty utilizing lipid as a fuel source while host tissues continue to oxidize lipids for energy.36 This has led to the hypothesis that diets relatively high in fat may be of benefit to the animal with cancer when compared to a diet high in simple carbohydrates. Further research may reveal that the type of fat, rather than the amount, may be of greater importance. In one study, mean nitrogen intake, nitrogen balance, in vitro lymphocyte mitogenesis, time for wound healing, the prevalence of wound complications, and the duration of hospitalization was significantly better in 85 surgical patients fed an omega-3 fatty acid supplement when compared to controls.37,38 Studies of polyunsaturated fatty acids (PUFA's) of the n-3 series, especially eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), indicate that these fatty acids may prevent the development of carcinogen-induced tumors, the growth of solid tumors, as well as the occurrence of cachexia and metastatic disease in experimental tumor models. Fatty acids of the n-3 series have been shown to normalize elevated blood lactic acid and insulin levels in non-malignant conditions . In contrast, PUFA's of the n-6 series appear to enhance tumor development and metastases. These data, along with the epidemiological findings of an inverse relationship between dietary n-3 fatty acid intake and incidence of some cancer, is the basis of research to evaluate the potential benefit of n-3 fatty acids in the prevention of cancer cachexia and therapy of malignancy in cancer patients.
One such study was recently completed in dogs with lymphoma.37 A double blind, randomized study was recently reported to evaluate the hypothesis that polyunsaturated n-3 fatty acids and arginine can improve metabolic parameters, decrease chemical indices of inflammation, enhance quality of life, and extend disease-free interval and survival time in dogs treated for lymphoma. In that study, dogs fed the experimental diet had significantly higher serum levels of polyunsaturated n-3 fatty acids docosahexaenoic acid (C22:6) and eicosapentaenoic acid (C20:5) as well as arginine when compared to controls. Both diets were formulated to be relatively low in simple carbohydrates, with moderate amounts of highly bioavailable proteins. This formulation is designed to enhance the effect of n-3 fatty acids. Higher serum levels of these n-3 fatty acids were associated with lesser plasma lactic acid responses to intravenous glucose and diet tolerance testing. Increasing C22:6 levels was significantly associated with longer disease free interval and survival time for dogs with stage III lymphoma fed the experimental diet.
Another study was recently completed that was designed to determine the effect of a diet supplemented with n-3 fatty acids and arginine on irradiated skin and oral mucosa, carbohydrate metabolism and quality of life in a group of dogs with nasal tumors.40 This study showed that fatty acids of the n-3 series normalize elevated blood lactic acid. In a dose dependent manner, n-3 fatty acids result in decreased histologic evidence of radiation damage to skin and mucosa and improve performance scores in dogs with malignant nasal tumors. This would obviously be of great benefit to the cancer patient receiving radiation therapy. These two studies confirm that diets supplemented with polyunsaturated n-3 fatty acids are of benefit for the cancer patient.
The bottom line is that n-3 fatty acids in moderate amounts appear to benefit the cancer patient. More specifically, a diet relatively high in n-3 fatty acids and relatively now in simple carbohydrates has been shown not only to improve alterations in metabolism associated with cancer, but also improve response to chemotherapy and decrease the adverse effects associated with radiation therapy.
The clinical impact of the abnormalities in lipid metabolism may be lessened with dietary therapy. In contrast to carbohydrates and proteins, some tumor cells have difficulty utilizing lipid as a fuel source while host tissues continue to oxidize lipids for energy.36 This has led to the hypothesis that diets relatively high in fat may be of benefit to the animal with cancer when compared to a diet high in simple carbohydrates. Further research may reveal that the type of fat, rather than the amount, may be of greater importance. In one study, mean nitrogen intake, nitrogen balance, in vitro lymphocyte mitogenesis, time for wound healing, the prevalence of wound complications, and the duration of hospitalization was significantly better in 85 surgical patients fed an omega-3 fatty acid supplement when compared to controls.37,38 Studies of polyunsaturated fatty acids (PUFA's) of the n-3 series, especially eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), indicate that these fatty acids may prevent the development of carcinogen-induced tumors, the growth of solid tumors, as well as the occurrence of cachexia and metastatic disease in experimental tumor models. Fatty acids of the n-3 series have been shown to normalize elevated blood lactic acid and insulin levels in non-malignant conditions . In contrast, PUFA's of the n-6 series appear to enhance tumor development and metastases. These data, along with the epidemiological findings of an inverse relationship between dietary n-3 fatty acid intake and incidence of some cancer, is the basis of research to evaluate the potential benefit of n-3 fatty acids in the prevention of cancer cachexia and therapy of malignancy in cancer patients.
One such study was recently completed in dogs with lymphoma.37 A double blind, randomized study was recently reported to evaluate the hypothesis that polyunsaturated n-3 fatty acids and arginine can improve metabolic parameters, decrease chemical indices of inflammation, enhance quality of life, and extend disease-free interval and survival time in dogs treated for lymphoma. In that study, dogs fed the experimental diet had significantly higher serum levels of polyunsaturated n-3 fatty acids docosahexaenoic acid (C22:6) and eicosapentaenoic acid (C20:5) as well as arginine when compared to controls. Both diets were formulated to be relatively low in simple carbohydrates, with moderate amounts of highly bioavailable proteins. This formulation is designed to enhance the effect of n-3 fatty acids. Higher serum levels of these n-3 fatty acids were associated with lesser plasma lactic acid responses to intravenous glucose and diet tolerance testing. Increasing C22:6 levels was significantly associated with longer disease free interval and survival time for dogs with stage III lymphoma fed the experimental diet.
Another study was recently completed that was designed to determine the effect of a diet supplemented with n-3 fatty acids and arginine on irradiated skin and oral mucosa, carbohydrate metabolism and quality of life in a group of dogs with nasal tumors.40 This study showed that fatty acids of the n-3 series normalize elevated blood lactic acid. In a dose dependent manner, n-3 fatty acids result in decreased histologic evidence of radiation damage to skin and mucosa and improve performance scores in dogs with malignant nasal tumors. This would obviously be of great benefit to the cancer patient receiving radiation therapy. These two studies confirm that diets supplemented with polyunsaturated n-3 fatty acids are of benefit for the cancer patient.
The bottom line is that n-3 fatty acids in moderate amounts appear to benefit the cancer patient. More specifically, a diet relatively high in n-3 fatty acids and relatively now in simple carbohydrates has been shown not only to improve alterations in metabolism associated with cancer, but also improve response to chemotherapy and decrease the adverse effects associated with radiation therapy.
Protein Metabolism
Cancer has been shown to result in decreased body muscle mass, skeletal protein synthesis, and alter nitrogen balance while concurrently increasing skeletal protein breakdown, liver protein synthesis, and whole body protein synthesis. 16-18 Tumors preferentially use protein for energy at the expense of the host. 16-18,21-25 Tumors preferentially utilize certain amino acids for gluconeogenesis, which results in abnormal amino acid profiles. These abnormal profiles have been documented in pet animals with a wide variety of cancers. The use of amino acids by the tumor for energy becomes clinically significant for the host when protein degradation and loss exceed synthesis. This can result in alterations in many important bodily functions such as immune response, gastrointestinal function and surgical healing.22,23
Knowledge that cancer preferentially utilizes amino acids and that some amino acids may be therapeutic may be of value when designing a diet for the cancer patient. Providing high quality amino acids or protein in the diet may be of critical importance for the veterinary cancer patient. A quality protein diet that is highly bioavailable may be ideal. Arginine, glycine, cystine and glutamine may be of specific value for therapeutic purposes.26-29 Arginine may stimulate lymphocyte blastogenesis. The addition of arginine to total parenteral nutrition solutions has been shown to decrease tumor growth and metastatic rate in some rodent systems.26,27 Some amino acids my decrease toxicity associated with chemotherapy. For example, glycine has been shown to reduce cisplatin-induced nephrotoxicity.. Cystine has been shown to be effective for reducing Heinz body anemia in cats. Glutamine has been shown to be effective for reducing histologic and clinical evidence of methotrexate-induced gastrointestinal toxicity in cats.
The bottom line is that a diet that has moderate amounts of highly bioavailable protein may be of value to the cancer patient. Certain amino acids such as glutamine, cystine, and arginine may also be beneficial for some cancer patients.32,33
Knowledge that cancer preferentially utilizes amino acids and that some amino acids may be therapeutic may be of value when designing a diet for the cancer patient. Providing high quality amino acids or protein in the diet may be of critical importance for the veterinary cancer patient. A quality protein diet that is highly bioavailable may be ideal. Arginine, glycine, cystine and glutamine may be of specific value for therapeutic purposes.26-29 Arginine may stimulate lymphocyte blastogenesis. The addition of arginine to total parenteral nutrition solutions has been shown to decrease tumor growth and metastatic rate in some rodent systems.26,27 Some amino acids my decrease toxicity associated with chemotherapy. For example, glycine has been shown to reduce cisplatin-induced nephrotoxicity.. Cystine has been shown to be effective for reducing Heinz body anemia in cats. Glutamine has been shown to be effective for reducing histologic and clinical evidence of methotrexate-induced gastrointestinal toxicity in cats.
The bottom line is that a diet that has moderate amounts of highly bioavailable protein may be of value to the cancer patient. Certain amino acids such as glutamine, cystine, and arginine may also be beneficial for some cancer patients.32,33
Carbohydrates, Proteins and Fats and Feeding the Cancer Patient
Carbohydrate Metabolism
Perhaps the most dramatic alterations in metabolism of animals with a wide variety of cancers occur in carbohydrate metabolism. For example, when dogs with a wide variety of malignancies without clinical evidence of cachexia were evaluated with an intravenous glucose tolerance test, lactate and insulin concentrations were significantly higher when compared to controls.19 The hyperlactatemia and hyperinsulinemia did not improve when these dogs were rendered free of all clinical evidence of cancer with either chemotherapy or surgery.15 Metabolic alterations result in part because tumors preferentially metabolize glucose for energy by anaerobic glycolysis forming lactate as an end product.2,16 The animal must then expend necessary energy via "futile cycling" to convert lactate to glucose by the Cori cycle resulting in a net energy gain by the tumor and a net energy loss by the host.14,16-19
The inability of some tumor bearing animals to tolerate glucose parenterally may have some bearing on the dietary management of the cancer patient. Logically, it can be concluded that diets high in simple carbohydrates may increase the total amount of lactate produced and the need for the host to utilize energy unwisely for conversion of lactate. This may have long-term detrimental effects on animals with cancer.
To test this hypothesis in the dog, a group of dogs with lymphoma were evaluated to determine if a diet high in simple carbohydrates is detrimental compared to a diet low in simple carbohydrates.20 In this study, dogs were randomized and fed isocaloric amounts of either a high fat diet, or a high carbohydrate diet before and after remission was attained with up to 5 dosages of doxorubicin chemotherapy. As hypothesized, the mean lactate and insulin levels from the dogs fed the high carbohydrate diet was significantly higher than the level from the dogs fed the fat diet after the dogs were fed the diets and put into remission with chemotherapy. Interestingly, dogs fed the high fat diet were more likely to go into remission. This study showed, therefore, that diet was effective for influencing response to therapy and select aspects of carbohydrate metabolism.
The bottom line is that simple carbohydrates may not be ideal for the cancer patient. Therefore, when considering a diet for a pet with cancer, a diet that has minimal amounts of simple carbohydrates may be ideal.
Perhaps the most dramatic alterations in metabolism of animals with a wide variety of cancers occur in carbohydrate metabolism. For example, when dogs with a wide variety of malignancies without clinical evidence of cachexia were evaluated with an intravenous glucose tolerance test, lactate and insulin concentrations were significantly higher when compared to controls.19 The hyperlactatemia and hyperinsulinemia did not improve when these dogs were rendered free of all clinical evidence of cancer with either chemotherapy or surgery.15 Metabolic alterations result in part because tumors preferentially metabolize glucose for energy by anaerobic glycolysis forming lactate as an end product.2,16 The animal must then expend necessary energy via "futile cycling" to convert lactate to glucose by the Cori cycle resulting in a net energy gain by the tumor and a net energy loss by the host.14,16-19
The inability of some tumor bearing animals to tolerate glucose parenterally may have some bearing on the dietary management of the cancer patient. Logically, it can be concluded that diets high in simple carbohydrates may increase the total amount of lactate produced and the need for the host to utilize energy unwisely for conversion of lactate. This may have long-term detrimental effects on animals with cancer.
To test this hypothesis in the dog, a group of dogs with lymphoma were evaluated to determine if a diet high in simple carbohydrates is detrimental compared to a diet low in simple carbohydrates.20 In this study, dogs were randomized and fed isocaloric amounts of either a high fat diet, or a high carbohydrate diet before and after remission was attained with up to 5 dosages of doxorubicin chemotherapy. As hypothesized, the mean lactate and insulin levels from the dogs fed the high carbohydrate diet was significantly higher than the level from the dogs fed the fat diet after the dogs were fed the diets and put into remission with chemotherapy. Interestingly, dogs fed the high fat diet were more likely to go into remission. This study showed, therefore, that diet was effective for influencing response to therapy and select aspects of carbohydrate metabolism.
The bottom line is that simple carbohydrates may not be ideal for the cancer patient. Therefore, when considering a diet for a pet with cancer, a diet that has minimal amounts of simple carbohydrates may be ideal.
Metabolic Changes Associated with Cancer Cachexia
Clinically, in many patients there are three phases associated with cancer cachexia.5 The first phase is the preclinical "silent" phase is where the patient is not exhibiting any clinical signs of disease, yet there is evidence of biochemical changes such as hyperlactatemia, hyperinsulinemia and alterations in amino acid and lipid profiles. All of these alterations are of impending clinical importance, but the alterations in carbohydrate metabolism appear to be quite profound resulting in the production of tremendous amounts of lactate through energy inefficient anaerobic metabolism. The second phase is the clinical phase where the patient begins to exhibit weight loss, anorexia, lethargy and early evidence of weight loss. These patients are more likely to exhibit side effects associated with chemotherapy, radiation therapy, immune modulation, and surgery. The third and final phase of cancer cachexia is an accentuated form of the second phase; it is associated with marked debilitation, weakness and biochemical evidence of negative nitrogen balance that is also associated with clinical pathologic changes such as hypoalbuminemia. Cancer patients begin to loose carbohydrate and protein stores within the body. Loss of fat depots is the noted in this third and final stage of the disease. These patients literally waste away due to the physical effects of the malignancy and the resulting cancer-induced alterations in metabolism.
The purpose of this article is to answer the following questions:
1. What clinically significant alterations in metabolism occur in animals with cancer cachexia?
2. How can knowledge about the metabolic alterations in metabolism change the way you use nutrition to treat your cancer. In other words: what nutrients should you feed your cancer patient?
3. Does surgery, chemotherapy or cancer increase or decrease the energy needs and the amount you should feed your patient?
4. Are there any data on the efficacy of the nutrients my clients constantly ask me about: vitamins, minerals, proteases, garlic, tea and shark cartilage?
5. What are the indications for intervening aggressively with appetite stimulants, tube feeding or total parenteral feeding for your cancer patients?
2. How can knowledge about the metabolic alterations in metabolism change the way you use nutrition to treat your cancer. In other words: what nutrients should you feed your cancer patient?
3. Does surgery, chemotherapy or cancer increase or decrease the energy needs and the amount you should feed your patient?
4. Are there any data on the efficacy of the nutrients my clients constantly ask me about: vitamins, minerals, proteases, garlic, tea and shark cartilage?
5. What are the indications for intervening aggressively with appetite stimulants, tube feeding or total parenteral feeding for your cancer patients?
Soy
Soybeans are the most widely used, least expensive, and least caloric way to get large amounts of protein with very little fat and no cholesterol. You can eat soybeans in many forms, including tofu, the beans themselves (also known as edamame), soy milk, miso, and soy powder.
There are a lot of health-related phytochemicals in soy. Protein kinase inhibitors help keep cell growth and activity normal. Phytosterols and saponins help regulate cholesterol. Phenolic acid and phytates are antioxidants.
Then there are the isoflavones, which are weak phytoestrogens. Isoflavone levels vary in different types of tofu and soy milk products. Your body's estrogen is much, much stronger than the estrogen-like isoflavones in soy. So if the weak soy substance replaces the natural high-strength estrogen in cells, then maybe the soy will protect against cancers that would prefer a stronger estrogen signal.
Soy is often promoted as a healthy protein alternative for people who would rather not eat meat. Research about the effects of soy on cancer risk reduction has been mixed. Much of it has come from observing cultures such as the Japanese, who eat much more soy and begin eating it at a much younger age than people in Western countries.
In fact, the average woman living in East Asia eats about 10 times the quantity of soy foods as the average woman in the United States. Yet, East Asian women have lower rates of hormone-receptor-positive breast cancer than women in the United States.
The "soy story" and its possible connection to breast cancer is complicated by other factors. Most women living in Asia depend on soy as their main source of protein. They consume only small amounts of beef, chicken, and pork—which means less animal fat and other possibly unhealthy substances (such as growth hormones and antibiotics) in these animal protein sources. Also, compared to the average woman in the United States, the average Asian woman:
eats more fresh vegetables
is closer to her ideal body weight
is more physically active
is less likely to consume significant amounts of alcohol
All of these other factors add up to produce a healthier lifestyle and a lower overall risk of breast cancer in Asian women living in Asia.
It's not clear if soy isoflavones affect breast cancer, especially hormone-receptor-positive breast cancers. Isoflavones may affect hormonal therapy's ability to do its job if both of these molecules compete to get into the same estrogen receptors. If isoflavones deliver a weaker estrogen signal to the receptor compared to tamoxifen (and your body's estrogen), then the isoflavones might be able to decrease breast cell growth that's estrogen-dependent. But if the isoflavones give breast cells a stronger estrogen signal than tamoxifen, that's a problem.
Until the issue becomes clearer, many doctors recommend that women who take hormonal therapy or who have estrogen-receptor-positive breast cancer avoid soy supplements because they contain high concentrations of isoflavones. But in general, it's fine to eat moderate amounts of soy foods as part of a balanced diet. One to three servings of soy a day (a serving is about a half cup) is similar to an average Japanese woman's daily soy intake. If you are taking hormonal therapy to fight off a hormone-receptor-positive breast cancer, and you are concerned about any phytoestrogen effects, ask your doctor or registered dietitian about how much soy you can eat.
Nutrition and Cancer: Exciting Advances for 2002!
Gregory K. Ogilvie, DVM, Diplomate ACVIM (Internal Medicine, Oncology) Professor and Head of Medical Oncology, Animal Cancer Center, Colorado State UniversityFt. Collins, CO, USA
Cancer is one of the most common diseases in dogs and cats in the United States, Western Europe and Japan. Cancer cachexia is the most common paraneoplastic syndrome in veterinary medicine. This paraneoplastic syndrome of dogs and cats with a wide variety of malignancies results in profound alterations in carbohydrate, protein and lipid metabolism that subsequently results in anorexia, fatigue, impaired immune function, poor performance and weight loss in the face of adequate nutritional intake.1 These profound alterations in carbohydrate, protein and lipid metabolism have been documented in dogs and probably in cats with cancer, even before evidence of cancer cachexia was clinically apparent.1-11
The importance of cancer cachexia is underscored by the knowledge that animals and people with cancer cachexia have a decreased quality of life, poor response to treatment, and a shortened survival time when compared to those with neoplastic diseases but do not exhibit clinical or biochemical signs associated with this condition.1-8 Therefore, it is obvious that cancer and cancer cachexia are of tremendous importance to the practicing veterinarian.
Nutritional therapy is a key component for the treatment of cancer cachexia and for actually helping control malignant disease in some situations. Specific nutrients can be used as powerful tools to reduce toxicity associated with chemotherapy, radiation therapy, and is important to enhance healing subsequent to surgery. There is little question that nutritional intervention must begin early and must be followed through aggressively to gain maximum benefit.....long before the patient exhibits evidence of weight loss, debilitation, or anorexia begin which can in turn enhance response to therapy and improve quality of life.
There are a lot of health-related phytochemicals in soy. Protein kinase inhibitors help keep cell growth and activity normal. Phytosterols and saponins help regulate cholesterol. Phenolic acid and phytates are antioxidants.
Then there are the isoflavones, which are weak phytoestrogens. Isoflavone levels vary in different types of tofu and soy milk products. Your body's estrogen is much, much stronger than the estrogen-like isoflavones in soy. So if the weak soy substance replaces the natural high-strength estrogen in cells, then maybe the soy will protect against cancers that would prefer a stronger estrogen signal.
Soy is often promoted as a healthy protein alternative for people who would rather not eat meat. Research about the effects of soy on cancer risk reduction has been mixed. Much of it has come from observing cultures such as the Japanese, who eat much more soy and begin eating it at a much younger age than people in Western countries.
In fact, the average woman living in East Asia eats about 10 times the quantity of soy foods as the average woman in the United States. Yet, East Asian women have lower rates of hormone-receptor-positive breast cancer than women in the United States.
The "soy story" and its possible connection to breast cancer is complicated by other factors. Most women living in Asia depend on soy as their main source of protein. They consume only small amounts of beef, chicken, and pork—which means less animal fat and other possibly unhealthy substances (such as growth hormones and antibiotics) in these animal protein sources. Also, compared to the average woman in the United States, the average Asian woman:
eats more fresh vegetables
is closer to her ideal body weight
is more physically active
is less likely to consume significant amounts of alcohol
All of these other factors add up to produce a healthier lifestyle and a lower overall risk of breast cancer in Asian women living in Asia.
It's not clear if soy isoflavones affect breast cancer, especially hormone-receptor-positive breast cancers. Isoflavones may affect hormonal therapy's ability to do its job if both of these molecules compete to get into the same estrogen receptors. If isoflavones deliver a weaker estrogen signal to the receptor compared to tamoxifen (and your body's estrogen), then the isoflavones might be able to decrease breast cell growth that's estrogen-dependent. But if the isoflavones give breast cells a stronger estrogen signal than tamoxifen, that's a problem.
Until the issue becomes clearer, many doctors recommend that women who take hormonal therapy or who have estrogen-receptor-positive breast cancer avoid soy supplements because they contain high concentrations of isoflavones. But in general, it's fine to eat moderate amounts of soy foods as part of a balanced diet. One to three servings of soy a day (a serving is about a half cup) is similar to an average Japanese woman's daily soy intake. If you are taking hormonal therapy to fight off a hormone-receptor-positive breast cancer, and you are concerned about any phytoestrogen effects, ask your doctor or registered dietitian about how much soy you can eat.
Nutrition and Cancer: Exciting Advances for 2002!
Gregory K. Ogilvie, DVM, Diplomate ACVIM (Internal Medicine, Oncology) Professor and Head of Medical Oncology, Animal Cancer Center, Colorado State UniversityFt. Collins, CO, USA
Cancer is one of the most common diseases in dogs and cats in the United States, Western Europe and Japan. Cancer cachexia is the most common paraneoplastic syndrome in veterinary medicine. This paraneoplastic syndrome of dogs and cats with a wide variety of malignancies results in profound alterations in carbohydrate, protein and lipid metabolism that subsequently results in anorexia, fatigue, impaired immune function, poor performance and weight loss in the face of adequate nutritional intake.1 These profound alterations in carbohydrate, protein and lipid metabolism have been documented in dogs and probably in cats with cancer, even before evidence of cancer cachexia was clinically apparent.1-11
The importance of cancer cachexia is underscored by the knowledge that animals and people with cancer cachexia have a decreased quality of life, poor response to treatment, and a shortened survival time when compared to those with neoplastic diseases but do not exhibit clinical or biochemical signs associated with this condition.1-8 Therefore, it is obvious that cancer and cancer cachexia are of tremendous importance to the practicing veterinarian.
Nutritional therapy is a key component for the treatment of cancer cachexia and for actually helping control malignant disease in some situations. Specific nutrients can be used as powerful tools to reduce toxicity associated with chemotherapy, radiation therapy, and is important to enhance healing subsequent to surgery. There is little question that nutritional intervention must begin early and must be followed through aggressively to gain maximum benefit.....long before the patient exhibits evidence of weight loss, debilitation, or anorexia begin which can in turn enhance response to therapy and improve quality of life.
Raw Food Diet
The raw food diet has become popular with some people who want to do anything they possibly can to improve their health. All the foods in the diet are eaten raw so that the food's chemical structure isn't changed. Proponents of the raw food diet believe that raw foods contain more beneficial enzymes than cooked food because heating food breaks down the enzymes.
While most raw food diets include only fruits, vegetables, nuts, and seeds, some raw diets include raw milk, meat, and eggs. Raw or undercooked meat and dairy products may contain bacteria, and eating them may make you sick. This is especially a concern if your immune system is compromised from breast cancer treatment. If you are interested in a raw food diet, avoid raw animal products.
Right now, there is no scientific evidence that a raw food diet will reduce breast cancer risk. Because the diet is rich in fruits, vegetables, and whole grains, it contains many phytochemicals that may provide a range of health benefits. Following a strict raw food diet that has no animal products will probably not give you enough protein, iron, calcium, and other important minerals, especially if you are having chemotherapy or other breast cancer treatment.More research is needed on the raw food diet and how it may affect breast cancer risk. If you're interested in raw foods, talk to your doctor and a registered dietitian to make sure you're getting enough nutrients and that your diet is properly balanced. You may be able to modify the raw food diet to meet your individual circumstances.
While most raw food diets include only fruits, vegetables, nuts, and seeds, some raw diets include raw milk, meat, and eggs. Raw or undercooked meat and dairy products may contain bacteria, and eating them may make you sick. This is especially a concern if your immune system is compromised from breast cancer treatment. If you are interested in a raw food diet, avoid raw animal products.
Right now, there is no scientific evidence that a raw food diet will reduce breast cancer risk. Because the diet is rich in fruits, vegetables, and whole grains, it contains many phytochemicals that may provide a range of health benefits. Following a strict raw food diet that has no animal products will probably not give you enough protein, iron, calcium, and other important minerals, especially if you are having chemotherapy or other breast cancer treatment.More research is needed on the raw food diet and how it may affect breast cancer risk. If you're interested in raw foods, talk to your doctor and a registered dietitian to make sure you're getting enough nutrients and that your diet is properly balanced. You may be able to modify the raw food diet to meet your individual circumstances.
Phytochemicals
Phytochemicals are compounds that are produced by plants ("phyto" means "plant"). They are found in fruits, vegetables, grains, beans, and other plants. Some of these phytochemicals are believed to protect cells from damage that could lead to cancer.
Some scientists think that you could reduce your cancer risk by as much as 40% by eating more vegetables, fruits, and other plant foods that have certain phytochemicals in them. Research has shown that some phytochemicals may:
help stop the formation of potential cancer-causing substances (carcinogens)
help stop carcinogens from attacking cells
help cells stop and wipe out any cancer-like changes
Some of the most beneficial phytochemicals are:
beta carotene and other carotenoids in fruits and vegetables
resveratrol in red wine
polyphenols in tea
isothiocyanates in cruciferous vegetables (members of the cabbage family that include bok choy, collards, broccoli, brussels sprouts, kohlrabi, kale, mustard greens, turnip greens, and cauliflower)
Because these phytochemicals are in the fruits, vegetables, beans, and grains you eat, it's fairly easy to include them in your diet. A carrot, for example, has more than 100 phytochemicals. Nutrition researchers estimate that more than 4,000 phytochemicals have been identified, but only about 150 have been studied in depth. More research is needed to find out which phytochemicals may offer benefits in reducing the risk of cancer.
Keep in mind that there is no evidence that taking phytochemical supplements is as good for you as eating the whole fruits, vegetables, beans and grains that contain them. Most experts strongly believe that it's the combination of these compounds and the other foods you eat that keeps your body healthy. Loading up on one or two phytochemicals in pill form probably won't be as beneficial as eating a balanced diet with a variety of foods that includes five or more cups of fruits and vegetables per day, and food from other plant sources, such as whole-grain breads, cereals, nuts, seeds, rice and pasta, and beans.
There are several main groups of health-promoting phytochemicals.
Flavonoids are found in lots of grains, vegetables, and fruits. The flavonoids in soybeans, chickpeas, and licorice may act a little bit like estrogen, a hormone that might affect the risk of breast cancer that depends on estrogen for its growth.
The estrogen-like compounds in these plants are called phytoestrogens. But most phytoestrogens have very weak estrogen-like activity. When a weak estrogen-like substance replaces your body's regular natural estrogen's position, then the weak substance can act as a relative anti-estrogen. By acting in this way, phytoestrogens might help work against breast cancer that depends on estrogen for its growth. But phytoestrogens are present in only small amounts in these foods. Learn more about the phytoestrogens in soy foods in the area about soy.
Researchers are studying flavonoids to see if they can reduce the risk of certain types of cancers and heart disease.
Antioxidants protect your body's cells from free radicals—unstable molecules created during normal cell functions. But pollution, radiation, cigarette smoke, and herbicides also can create free radicals. Free radicals can damage a cell's genetic parts and may trigger the cell to grow out of control. These changes may contribute to the development of cancer and other diseases.
Antioxidants are found in broccoli, brussels sprouts, cabbage, cauliflower, tomatoes, corn, carrots, mangos, sweet potatoes, soybeans, cantaloupe, oranges, spinach, nuts, lettuce, celery, liver, fish oil, seeds, grains, kale, beets, red peppers, potatoes, blueberries, strawberries, and black and green tea. As a rule, dark-colored fruits and vegetables have more antioxidants than other fruits and vegetables.
Carotenoids, which give carrots, yams, cantaloupe, squash, and apricots their orange color, may help reduce the risk of cancer. Anthocyanins, which give grapes, blueberries, cranberries, and raspberries their dark color, have been shown in the laboratory to have anti-inflammatory and anti-tumor properties.
Sulfides, found in garlic and onions, may strengthen the immune system.
Much of the evidence so far on the effects of phytochemicals comes from observing people who eat mainly plant-based diets. These people appear to have markedly lower rates of certain types of cancers and heart disease. Some of the associations between specific phytochemicals and cancer risk reduction are very persuasive, but more research is needed. So far there is no conclusive evidence that any phytochemicals will help reduce the risk of getting cancer or help get rid of cancer if you have it.
There will never be just one vital food ingredient that you need to include in your diet. Registered dietitians and other healthcare professionals will always recommend eating a balanced diet that includes a variety of vegetables, fruits, legumes, and whole grains.
Some scientists think that you could reduce your cancer risk by as much as 40% by eating more vegetables, fruits, and other plant foods that have certain phytochemicals in them. Research has shown that some phytochemicals may:
help stop the formation of potential cancer-causing substances (carcinogens)
help stop carcinogens from attacking cells
help cells stop and wipe out any cancer-like changes
Some of the most beneficial phytochemicals are:
beta carotene and other carotenoids in fruits and vegetables
resveratrol in red wine
polyphenols in tea
isothiocyanates in cruciferous vegetables (members of the cabbage family that include bok choy, collards, broccoli, brussels sprouts, kohlrabi, kale, mustard greens, turnip greens, and cauliflower)
Because these phytochemicals are in the fruits, vegetables, beans, and grains you eat, it's fairly easy to include them in your diet. A carrot, for example, has more than 100 phytochemicals. Nutrition researchers estimate that more than 4,000 phytochemicals have been identified, but only about 150 have been studied in depth. More research is needed to find out which phytochemicals may offer benefits in reducing the risk of cancer.
Keep in mind that there is no evidence that taking phytochemical supplements is as good for you as eating the whole fruits, vegetables, beans and grains that contain them. Most experts strongly believe that it's the combination of these compounds and the other foods you eat that keeps your body healthy. Loading up on one or two phytochemicals in pill form probably won't be as beneficial as eating a balanced diet with a variety of foods that includes five or more cups of fruits and vegetables per day, and food from other plant sources, such as whole-grain breads, cereals, nuts, seeds, rice and pasta, and beans.
There are several main groups of health-promoting phytochemicals.
Flavonoids are found in lots of grains, vegetables, and fruits. The flavonoids in soybeans, chickpeas, and licorice may act a little bit like estrogen, a hormone that might affect the risk of breast cancer that depends on estrogen for its growth.
The estrogen-like compounds in these plants are called phytoestrogens. But most phytoestrogens have very weak estrogen-like activity. When a weak estrogen-like substance replaces your body's regular natural estrogen's position, then the weak substance can act as a relative anti-estrogen. By acting in this way, phytoestrogens might help work against breast cancer that depends on estrogen for its growth. But phytoestrogens are present in only small amounts in these foods. Learn more about the phytoestrogens in soy foods in the area about soy.
Researchers are studying flavonoids to see if they can reduce the risk of certain types of cancers and heart disease.
Antioxidants protect your body's cells from free radicals—unstable molecules created during normal cell functions. But pollution, radiation, cigarette smoke, and herbicides also can create free radicals. Free radicals can damage a cell's genetic parts and may trigger the cell to grow out of control. These changes may contribute to the development of cancer and other diseases.
Antioxidants are found in broccoli, brussels sprouts, cabbage, cauliflower, tomatoes, corn, carrots, mangos, sweet potatoes, soybeans, cantaloupe, oranges, spinach, nuts, lettuce, celery, liver, fish oil, seeds, grains, kale, beets, red peppers, potatoes, blueberries, strawberries, and black and green tea. As a rule, dark-colored fruits and vegetables have more antioxidants than other fruits and vegetables.
Carotenoids, which give carrots, yams, cantaloupe, squash, and apricots their orange color, may help reduce the risk of cancer. Anthocyanins, which give grapes, blueberries, cranberries, and raspberries their dark color, have been shown in the laboratory to have anti-inflammatory and anti-tumor properties.
Sulfides, found in garlic and onions, may strengthen the immune system.
Much of the evidence so far on the effects of phytochemicals comes from observing people who eat mainly plant-based diets. These people appear to have markedly lower rates of certain types of cancers and heart disease. Some of the associations between specific phytochemicals and cancer risk reduction are very persuasive, but more research is needed. So far there is no conclusive evidence that any phytochemicals will help reduce the risk of getting cancer or help get rid of cancer if you have it.
There will never be just one vital food ingredient that you need to include in your diet. Registered dietitians and other healthcare professionals will always recommend eating a balanced diet that includes a variety of vegetables, fruits, legumes, and whole grains.
Omega-3 Fatty Acids
Omega-3 fatty acids are important nutrients involved in many body activities, especially immune system responses. Your body doesn't produce omega-3 fatty acids and must get them from the food you eat.
Research has shown that omega-3 fatty acids can help reduce the risk of heart disease by decreasing the risk of arrhythmias (abnormal heart rhythms), which can lead to sudden cardiac death. Omega-3 fatty acids also slow the growth of plaque in arteries and reduce levels of the unhealthy type of cholesterol (low-density lipoproteins) and triglycerides in your blood.
Omega-3 fatty acids are a good source of lignans—compounds that may have a weak estrogen effect. When a weak estrogen-like substance takes the place of your body's natural strong estrogen in a breast cell's estrogen receptor, then the weak substance can act as a relative anti-estrogen. By acting in this way, lignans might help work against breast cancer that depends on estrogen for its growth. But research so far on whether omega-3 fatty acids affect breast cancer risk has shown no conclusive association.
The highest concentrations of omega-3 fatty acids are found in coldwater fish, such as sardines, salmon, herring, tuna, cod, mackerel, halibut, and shark. These fatty acids are also found in lower concentrations in flaxseed, walnuts, Great Northern beans, kidney beans, navy beans, and soybeans. Some registered dietitians recommend eating a diet rich in fish with high levels of omega-3 fatty acids or eating one or two teaspoons of flaxseed every day.
But eating fish has become more of a health concern. Many fish with high levels of omega-3 fatty acids caught in the wild also have high levels of mercury and other environmental pollutants. Research on farm-raised salmon (the most popular farm-raised fish) found that it had higher levels of toxins (other than mercury) than fish caught in the wild. The levels of toxins in other types of wild fish compared to those in farm-raised fish aren't known. Some waters are probably safer than others for wild fish, and some farms are likely to be more health-conscious than others. For now, experts recommend varying the type of fish you eat to reduce the risk of eating too many contaminants. They also recommend eating wild-caught fish about twice a week and farm-raised salmon only about once a month.
Research has shown that omega-3 fatty acids can help reduce the risk of heart disease by decreasing the risk of arrhythmias (abnormal heart rhythms), which can lead to sudden cardiac death. Omega-3 fatty acids also slow the growth of plaque in arteries and reduce levels of the unhealthy type of cholesterol (low-density lipoproteins) and triglycerides in your blood.
Omega-3 fatty acids are a good source of lignans—compounds that may have a weak estrogen effect. When a weak estrogen-like substance takes the place of your body's natural strong estrogen in a breast cell's estrogen receptor, then the weak substance can act as a relative anti-estrogen. By acting in this way, lignans might help work against breast cancer that depends on estrogen for its growth. But research so far on whether omega-3 fatty acids affect breast cancer risk has shown no conclusive association.
The highest concentrations of omega-3 fatty acids are found in coldwater fish, such as sardines, salmon, herring, tuna, cod, mackerel, halibut, and shark. These fatty acids are also found in lower concentrations in flaxseed, walnuts, Great Northern beans, kidney beans, navy beans, and soybeans. Some registered dietitians recommend eating a diet rich in fish with high levels of omega-3 fatty acids or eating one or two teaspoons of flaxseed every day.
But eating fish has become more of a health concern. Many fish with high levels of omega-3 fatty acids caught in the wild also have high levels of mercury and other environmental pollutants. Research on farm-raised salmon (the most popular farm-raised fish) found that it had higher levels of toxins (other than mercury) than fish caught in the wild. The levels of toxins in other types of wild fish compared to those in farm-raised fish aren't known. Some waters are probably safer than others for wild fish, and some farms are likely to be more health-conscious than others. For now, experts recommend varying the type of fish you eat to reduce the risk of eating too many contaminants. They also recommend eating wild-caught fish about twice a week and farm-raised salmon only about once a month.
Mushrooms
Mushrooms contain a substance called conjugated linoleic acid that, according to recent research, appears to inhibit aromatase activity. Aromatase is an enzyme that helps the body make estrogen, so if there's less aromatase, there's less estrogen. Since many breast cancers depend on estrogen to grow, less estrogen may mean less breast cancer.
The same logic explains why aromatase inhibitors are used as adjuvant therapy (treatment after the main treatment) to prevent certain types of early breast cancer from coming back.
White button mushrooms were the focus of research, since they are the most commonly eaten type. Conjugated linoleic acid is also found in portobello, crimini, shiitake, and stuffing mushrooms. According to the study, 100 grams (3.5 ounces) or even less per day could prevent breast cancer growth and the benefit of conjugated linoleic acid appears to be gained whether the mushrooms are eaten raw or cooked.
Research on mushrooms has not yet been done in humans, but most dietitians agree that a diet rich in plant foods may be healthier than a diet that contains a lot of animal products. They also believe that the healthful compounds in different foods work together to provide health benefits. Instead of relying on a particular food in huge quantities, aim for a balanced diet with a variety of foods. And if you like mushrooms, include them as part of your overall diet plan in salads, sandwiches, soups, etc.
The same logic explains why aromatase inhibitors are used as adjuvant therapy (treatment after the main treatment) to prevent certain types of early breast cancer from coming back.
White button mushrooms were the focus of research, since they are the most commonly eaten type. Conjugated linoleic acid is also found in portobello, crimini, shiitake, and stuffing mushrooms. According to the study, 100 grams (3.5 ounces) or even less per day could prevent breast cancer growth and the benefit of conjugated linoleic acid appears to be gained whether the mushrooms are eaten raw or cooked.
Research on mushrooms has not yet been done in humans, but most dietitians agree that a diet rich in plant foods may be healthier than a diet that contains a lot of animal products. They also believe that the healthful compounds in different foods work together to provide health benefits. Instead of relying on a particular food in huge quantities, aim for a balanced diet with a variety of foods. And if you like mushrooms, include them as part of your overall diet plan in salads, sandwiches, soups, etc.
Macrobiotic Diet
The macrobiotic diet has become popular among many women who want to do whatever they can to lower their risk of getting breast cancer for the first time or reduce the risk of the breast cancer coming back. Vegetables and whole grains are the centerpiece of the macrobiotic diet. Most foods are processed very little, and eating dairy products, red meat, coffee, eggs, and sugar is discouraged. Vitamins and supplements are also discouraged.
The macrobiotic diet is part of a broader macrobiotic philosophy of life that emphasizes physical activity and advocates limiting exposure to pesticides and chemicals as well as electromagnetic radiation. Macrobiotics also recommends specific ways of cooking food and using only pans and utensils made of wood, glass, steel, or enamel.
Studies of women who followed a macrobiotic diet showed that compared to other women they had slightly lower estrogen levels, which may lower the risk of breast cancer that depends on estrogen for its growth. Right now, there is no scientific evidence that a macrobiotic diet will reduce breast cancer risk. Because the diet is rich in vegetables and whole grains, it contains many phytochemicals that may provide a range of health benefits. Following a strict macrobiotic diet that has no animal products will probably not give you enough protein, iron, calcium, and other important minerals, especially if you are having chemotherapy or other breast cancer treatment.
More research is needed on the macrobiotic diet and how it may affect breast cancer risk. If you're interested in macrobiotics, talk to your doctor and a registered dietitian to make sure you're getting enough nutrients and that your diet is properly balanced. You may be able to modify the macrobiotic diet to meet your individual circumstances.
The macrobiotic diet is part of a broader macrobiotic philosophy of life that emphasizes physical activity and advocates limiting exposure to pesticides and chemicals as well as electromagnetic radiation. Macrobiotics also recommends specific ways of cooking food and using only pans and utensils made of wood, glass, steel, or enamel.
Studies of women who followed a macrobiotic diet showed that compared to other women they had slightly lower estrogen levels, which may lower the risk of breast cancer that depends on estrogen for its growth. Right now, there is no scientific evidence that a macrobiotic diet will reduce breast cancer risk. Because the diet is rich in vegetables and whole grains, it contains many phytochemicals that may provide a range of health benefits. Following a strict macrobiotic diet that has no animal products will probably not give you enough protein, iron, calcium, and other important minerals, especially if you are having chemotherapy or other breast cancer treatment.
More research is needed on the macrobiotic diet and how it may affect breast cancer risk. If you're interested in macrobiotics, talk to your doctor and a registered dietitian to make sure you're getting enough nutrients and that your diet is properly balanced. You may be able to modify the macrobiotic diet to meet your individual circumstances.
Lycopene
Lycopene makes tomatoes red and gives other orangey fruits and vegetables their color. Processed tomatoes have the highest amounts of lycopene, but watermelon, pink grapefruit, and fresh tomatoes are also good sources. Some studies suggest that eating processed tomatoes with some oil or fat (for instance, tomato sauce) makes it easier for your body to absorb lycopene, compared to drinking raw tomato juice.
Lycopene is a powerful antioxidant. Studies suggest that people who eat a lot of tomato products have a lower risk of cancer of the lungs, prostate, and stomach. Lycopene may also help protect against cancers of the cervix, breast, pancreas, colon, and esophagus, but that has not been proven yet.But if you like tomatoes, there is no downside to eating a diet full of them, so enjoy
Lycopene is a powerful antioxidant. Studies suggest that people who eat a lot of tomato products have a lower risk of cancer of the lungs, prostate, and stomach. Lycopene may also help protect against cancers of the cervix, breast, pancreas, colon, and esophagus, but that has not been proven yet.But if you like tomatoes, there is no downside to eating a diet full of them, so enjoy
Garlic
Garlic is closely related to onions, leeks, shallots, scallions, and chives. For many years, it's been claimed that garlic can help fight cancer and infection. It's also said that garlic may be beneficial for stomach and abdominal problems.
Garlic contains many sulfides, one of which is alliin. When garlic bulbs are crushed, alliin is converted to another compound, allicin. Allicin seems to be one of the main active compounds in garlic and gives the root both its odor and its health benefits. Garlic also is an antioxidant.
Garlic may reduce the levels of Helicobacter pylori, a bacterium that can cause stomach ulcers and has been linked to stomach cancer. Other research results on the beneficial effects of garlic on cancer have been mixed.
There are many opinions on how the preparation and amount of garlic eaten may affect your health. Cooking a clove of garlic or cutting it changes the amount and type of the garlic's active compounds. Because of this, some people suggest eating it raw.
Eating large amounts of garlic, especially raw, may irritate your gastrointestinal tract, causing stomach upset and gas. But using a couple of cloves in pasta sauce, in salad dressing, or on garlic bread, even every day, shouldn't be a problem.
Garlic contains many sulfides, one of which is alliin. When garlic bulbs are crushed, alliin is converted to another compound, allicin. Allicin seems to be one of the main active compounds in garlic and gives the root both its odor and its health benefits. Garlic also is an antioxidant.
Garlic may reduce the levels of Helicobacter pylori, a bacterium that can cause stomach ulcers and has been linked to stomach cancer. Other research results on the beneficial effects of garlic on cancer have been mixed.
There are many opinions on how the preparation and amount of garlic eaten may affect your health. Cooking a clove of garlic or cutting it changes the amount and type of the garlic's active compounds. Because of this, some people suggest eating it raw.
Eating large amounts of garlic, especially raw, may irritate your gastrointestinal tract, causing stomach upset and gas. But using a couple of cloves in pasta sauce, in salad dressing, or on garlic bread, even every day, shouldn't be a problem.
Flaxseed
Flaxseed, also known as linseed, has been talked about since the 1950s as a potential cancer-fighting food. The grain is available as flour, meal, and seeds. It's found in some multi-grain breads, cereals, breakfast bars, and muffins. The toasted seeds can be sprinkled into salads, yogurt, or smoothies.
Just like omega-3 fatty acids, flaxseed is a good source of lignans—compounds that may have a weak estrogen effect. When a weak estrogen-like substance takes the place of your body's natural strong estrogen in a breast cell's estrogen receptor, then the weak substance can act as a relative anti-estrogen. By acting in this way, lignans might help work against breast cancer that depends on estrogen for its growth. The lignans are concentrated in the hull of the flaxseed. If the seeds are ground up, your body has an easier time getting to the lignans.
Most of the evidence of the protective effects of flaxseed has come from a few small studies done in animals. Research on flaxseed in humans is needed to study its possible effects on cancer.
Flaxseed can help keep your cholesterol down and your bowel health up. The oil in flaxseed, alpha-linoleic acid, is an omega-3 essential fatty acid. And flaxseed is high in fiber. If you choose to eat it, start with a small amount and make sure you drink plenty of water. The U.S. Department of Agriculture makes no recommendation about the amount of flaxseed you should eat each day. But many dietitians advise eating one or two tablespoons of ground flaxseed meal daily.
Just like omega-3 fatty acids, flaxseed is a good source of lignans—compounds that may have a weak estrogen effect. When a weak estrogen-like substance takes the place of your body's natural strong estrogen in a breast cell's estrogen receptor, then the weak substance can act as a relative anti-estrogen. By acting in this way, lignans might help work against breast cancer that depends on estrogen for its growth. The lignans are concentrated in the hull of the flaxseed. If the seeds are ground up, your body has an easier time getting to the lignans.
Most of the evidence of the protective effects of flaxseed has come from a few small studies done in animals. Research on flaxseed in humans is needed to study its possible effects on cancer.
Flaxseed can help keep your cholesterol down and your bowel health up. The oil in flaxseed, alpha-linoleic acid, is an omega-3 essential fatty acid. And flaxseed is high in fiber. If you choose to eat it, start with a small amount and make sure you drink plenty of water. The U.S. Department of Agriculture makes no recommendation about the amount of flaxseed you should eat each day. But many dietitians advise eating one or two tablespoons of ground flaxseed meal daily.
Foods To Consider
Most nutrition researchers believe that the healthful compounds in different foods work together to provide health benefits. The benefits of any single food must be evaluated as a part of your whole diet.
Instead of relying on a particular food in huge quantities, aim for a balanced diet with a variety of foods that includes:
five or more cups of fruits and vegetables per day, and
food from other plant sources, such as whole-grain breads and cereals, nuts, seeds, rice, pasta, and beans.
Most dietitians agree that a diet rich in plant foods may be healthier than a diet that contains a lot of animal products. In this section you can read about the compounds in plants that are good for your health.
Instead of relying on a particular food in huge quantities, aim for a balanced diet with a variety of foods that includes:
five or more cups of fruits and vegetables per day, and
food from other plant sources, such as whole-grain breads and cereals, nuts, seeds, rice, pasta, and beans.
Most dietitians agree that a diet rich in plant foods may be healthier than a diet that contains a lot of animal products. In this section you can read about the compounds in plants that are good for your health.
Warnings about Diets That Claim to Cure Cancer
Hundreds of scientific studies support a diet that contains a variety of foods as the cornerstone of healthy eating. Most extreme diets that limit you to eating only one or two foods aren't healthy. The bottom line: There is no scientific evidence that any special diet can cure cancer.
Alternative diets that rely on special supplements or injections, fasting for extended periods, or enemas can be harmful to your health—especially if you're getting treatments for breast cancer. If you're in treatment, you need to make sure your body is getting enough nutrients and calories so it can function and heal.
Here are some of the most well-known diets that claim to help "cure" cancer. This is for your information only. breastcancer.org DOES NOT ENDORSE any of these diets.
Livingston-Wheeler Therapy
Livingston-Wheeler therapy includes vaccine, antibiotics, vitamin and mineral supplements, digestive enzymes, enemas, and a vegetarian diet. The safety of this diet has never been established. There is no scientific evidence that Livingston-Wheeler therapy effectively treats breast cancer or any other disease.
Gerson Therapy
Gerson therapy is a metabolic therapy, meaning it focuses on the chemical functions of the body. Gerson therapy uses a combination of special diets and other elements to try to remove so-called "toxins" from the body that are supposedly causing the disease. Gerson therapy practitioners believe that women with breast cancer have too much sodium in their bodies—so much so that it outweighs the potassium. Gerson therapy involves a very strict low-salt, low-fat, vegetarian diet, and includes drinking juice from approximately 20 pounds of freshly squeezed fruits and vegetables per day. It also includes coffee enemas. There is no scientific evidence that Gerson therapy effectively reduces breast cancer progression or improves survival. Harmful side effects may include malnutrition, severe dehydration, and electrolyte imbalances. Regular enemas can also cause trauma to the anus and rectum (the last two parts of your bowel).
Kelly and Gonzalez Treatments
Kelly and Gonzalez treatments are also metabolic therapies that try to remove so-called "toxins" from the body. The Kelly treatment involves up to 150 daily supplements, fasting, exercising, and using laxatives or coffee enemas, chiropractic adjustments, and prayer. The Gonzalez treatment is similar. They both focus on "detoxifying" the body and bringing it "back into balance." There is no scientific evidence that Kelly or Gonzalez therapies effectively treat breast cancer or that they are safe for your health. Harmful side effects may include malnutrition, severe dehydration, and electrolyte imbalances. Regular enemas can also cause trauma to the anus and rectum (the last two parts of your bowel).
Alternative diets that rely on special supplements or injections, fasting for extended periods, or enemas can be harmful to your health—especially if you're getting treatments for breast cancer. If you're in treatment, you need to make sure your body is getting enough nutrients and calories so it can function and heal.
Here are some of the most well-known diets that claim to help "cure" cancer. This is for your information only. breastcancer.org DOES NOT ENDORSE any of these diets.
Livingston-Wheeler Therapy
Livingston-Wheeler therapy includes vaccine, antibiotics, vitamin and mineral supplements, digestive enzymes, enemas, and a vegetarian diet. The safety of this diet has never been established. There is no scientific evidence that Livingston-Wheeler therapy effectively treats breast cancer or any other disease.
Gerson Therapy
Gerson therapy is a metabolic therapy, meaning it focuses on the chemical functions of the body. Gerson therapy uses a combination of special diets and other elements to try to remove so-called "toxins" from the body that are supposedly causing the disease. Gerson therapy practitioners believe that women with breast cancer have too much sodium in their bodies—so much so that it outweighs the potassium. Gerson therapy involves a very strict low-salt, low-fat, vegetarian diet, and includes drinking juice from approximately 20 pounds of freshly squeezed fruits and vegetables per day. It also includes coffee enemas. There is no scientific evidence that Gerson therapy effectively reduces breast cancer progression or improves survival. Harmful side effects may include malnutrition, severe dehydration, and electrolyte imbalances. Regular enemas can also cause trauma to the anus and rectum (the last two parts of your bowel).
Kelly and Gonzalez Treatments
Kelly and Gonzalez treatments are also metabolic therapies that try to remove so-called "toxins" from the body. The Kelly treatment involves up to 150 daily supplements, fasting, exercising, and using laxatives or coffee enemas, chiropractic adjustments, and prayer. The Gonzalez treatment is similar. They both focus on "detoxifying" the body and bringing it "back into balance." There is no scientific evidence that Kelly or Gonzalez therapies effectively treat breast cancer or that they are safe for your health. Harmful side effects may include malnutrition, severe dehydration, and electrolyte imbalances. Regular enemas can also cause trauma to the anus and rectum (the last two parts of your bowel).
Can Food Reduce Your Risk of Breast Cancer
Expert Answers
"It can be confusing to read all the stories in the media about certain foods. Nutrition is a young science. Each study is filling in another small piece of knowledge."
Diana Dyer, M.S., R.D., three-time cancer survivor
No food or diet can prevent you from getting breast cancer. But some foods can make your body the healthiest it can be, boost your immune system, and help keep your risk for breast cancer as low as possible. And no food or diet can cure cancer, though some of them may help control treatment side effects or help your body get well after treatment. Some food choices may help cancer treatment work more effectively or may help keep you healthy. Others can be dangerous and can interfere with treatment and recovery.
Healthy Weight Reduces Risk First-time Breast Cancer and Recurrence
Maintaining a healthy weight may help reduce the risk of breast cancer coming back. In a 2005 study, researchers found that women who gained weight after their breast cancer diagnosis had an increased risk of recurrence.
Studies on maintaining a healthy weight and lowering the risk of a first-time breast cancer suggest that overweight women have an increased risk of breast cancer after menopause compared to women at a healthy weight.
If you're not sure what your healthy weight should be, use some of the tips and tools available on the Assess Your Weight page. A healthy eating plan should include some physical activity. Aim for three to four hours of walking per week to start. If you're having treatment right now, you may need to start slowly and work up to this.
Low-fat Diet May Reduce Risk of Recurrence and First-time Breast Cancer
Sticking to a low-fat diet may help reduce the risk of breast cancer coming back. One study in which women got only about 25% of their daily calories from fat found a lower risk of recurrence, mostly in women with a prior estrogen-receptor-negative breast cancer. It will take more than this one study to know who is most likely to get the biggest benefit from specific dietary changes. But no matter what kind of cancer you've had, you might get significant benefit from lowering the amount of fat in your diet. Plus, other healthy choices are more likely to come with a low-fat diet, such as eating more fruits and vegetables and losing weight. All these changes together may help lower your risk of recurrence.
The Women's Health Initiative Trial compared the breast cancer risk of post-menopausal women who ate a low-fat diet to those who continued to eat their regular diet. The researchers didn't find any significant differences in breast cancer risk between the two groups. But the study did suggest that a low-fat diet may reduce the risk of first-time breast cancer for women whose diets are very high in fat to begin with. More research is needed to determine if this relationship becomes stronger over time. And reducing fat and increasing fruits and vegetables and whole grains in your diet will ensure your body is getting enough nutrients and contribute to your overall health. Also, a low-fat diet will probably help you lose weight, if you are trying to do that.
No Foods or Supplements Are Linked Specifically to Breast Cancer
There is no strong evidence that any specific foods or supplements will lower the risk of getting breast cancer or reduce the risk of recurrence.
Research has shown that getting the nutrients you need from a variety of foods, especially fruits, vegetables, and whole grains, can make you feel your best and give your body the energy it needs. You can get many of the nutrients you need from the food you eat. If you're considering taking supplements, it's a good idea to have a registered dietitian evaluate your diet. You may need a bit more of a specific nutrient like folate or vitamin A. That's why women both with or without a prior breast cancer often take a multiple vitamin and mineral supplement. Many women also need calcium supplements to meet their daily calcium requirements.
Research on Diet and Breast Cancer Is Ongoing
Studies are looking at the relationship between diet and breast cancer risk and the risk of recurrence. The Women's Health Initiative Trial suggested that a diet very low in fat may reduce the risk of breast cancer.
In the Women's Healthy Eating and Living (WHEL) study, women diagnosed with breast cancer were asked to adopt a diet that was rich in vegetables and fiber and low in fat to see if it could increase survival and reduce the risk of the cancer coming back. While the diet didn't seem to have any effect on survival or recurrence risk, it could be because the women in the study didn't meet the targets for vegetable and fiber consumption or fat reduction.
More research is needed in this important area for women who are interested in eating well to reduce their risk of ever getting breast cancer or the breast cancer coming back.
In the meantime, here's what dietitians suggest:
Keep your body weight in a healthy range for your height and frame. Body mass index, though not a perfect measurement, can help you estimate your healthy weight.
Eat plenty of vegetables and fruit (more than five cups a day).
Try to limit your fat intake to less than 20% of your total calories per day. This is an extremely small amount of fat to eat (an average amount is about 30 to 35% of total calories per day). Start by eliminating some foods with the highest fat content (like fried foods and margarine) and gradually lower the amount of fat you eat.
Eat foods high in omega-3 fatty acids.
Avoid trans fats, red meats, and charred or smoked foods.
You'll find that processed foods generally don't fit in this type of diet as well as fresh foods do.
To develop a healthy diet that meets your needs, seek advice from a registered dietitian. He or she will thoroughly evaluate your medical, diet, and weight history. Then the registered dietitian will work with you on an individualized plan to meet all your goals:
keep your risk of breast cancer as low as possible
provide you with good nutrition
keep you as healthy as possible
"It can be confusing to read all the stories in the media about certain foods. Nutrition is a young science. Each study is filling in another small piece of knowledge."
Diana Dyer, M.S., R.D., three-time cancer survivor
No food or diet can prevent you from getting breast cancer. But some foods can make your body the healthiest it can be, boost your immune system, and help keep your risk for breast cancer as low as possible. And no food or diet can cure cancer, though some of them may help control treatment side effects or help your body get well after treatment. Some food choices may help cancer treatment work more effectively or may help keep you healthy. Others can be dangerous and can interfere with treatment and recovery.
Healthy Weight Reduces Risk First-time Breast Cancer and Recurrence
Maintaining a healthy weight may help reduce the risk of breast cancer coming back. In a 2005 study, researchers found that women who gained weight after their breast cancer diagnosis had an increased risk of recurrence.
Studies on maintaining a healthy weight and lowering the risk of a first-time breast cancer suggest that overweight women have an increased risk of breast cancer after menopause compared to women at a healthy weight.
If you're not sure what your healthy weight should be, use some of the tips and tools available on the Assess Your Weight page. A healthy eating plan should include some physical activity. Aim for three to four hours of walking per week to start. If you're having treatment right now, you may need to start slowly and work up to this.
Low-fat Diet May Reduce Risk of Recurrence and First-time Breast Cancer
Sticking to a low-fat diet may help reduce the risk of breast cancer coming back. One study in which women got only about 25% of their daily calories from fat found a lower risk of recurrence, mostly in women with a prior estrogen-receptor-negative breast cancer. It will take more than this one study to know who is most likely to get the biggest benefit from specific dietary changes. But no matter what kind of cancer you've had, you might get significant benefit from lowering the amount of fat in your diet. Plus, other healthy choices are more likely to come with a low-fat diet, such as eating more fruits and vegetables and losing weight. All these changes together may help lower your risk of recurrence.
The Women's Health Initiative Trial compared the breast cancer risk of post-menopausal women who ate a low-fat diet to those who continued to eat their regular diet. The researchers didn't find any significant differences in breast cancer risk between the two groups. But the study did suggest that a low-fat diet may reduce the risk of first-time breast cancer for women whose diets are very high in fat to begin with. More research is needed to determine if this relationship becomes stronger over time. And reducing fat and increasing fruits and vegetables and whole grains in your diet will ensure your body is getting enough nutrients and contribute to your overall health. Also, a low-fat diet will probably help you lose weight, if you are trying to do that.
No Foods or Supplements Are Linked Specifically to Breast Cancer
There is no strong evidence that any specific foods or supplements will lower the risk of getting breast cancer or reduce the risk of recurrence.
Research has shown that getting the nutrients you need from a variety of foods, especially fruits, vegetables, and whole grains, can make you feel your best and give your body the energy it needs. You can get many of the nutrients you need from the food you eat. If you're considering taking supplements, it's a good idea to have a registered dietitian evaluate your diet. You may need a bit more of a specific nutrient like folate or vitamin A. That's why women both with or without a prior breast cancer often take a multiple vitamin and mineral supplement. Many women also need calcium supplements to meet their daily calcium requirements.
Research on Diet and Breast Cancer Is Ongoing
Studies are looking at the relationship between diet and breast cancer risk and the risk of recurrence. The Women's Health Initiative Trial suggested that a diet very low in fat may reduce the risk of breast cancer.
In the Women's Healthy Eating and Living (WHEL) study, women diagnosed with breast cancer were asked to adopt a diet that was rich in vegetables and fiber and low in fat to see if it could increase survival and reduce the risk of the cancer coming back. While the diet didn't seem to have any effect on survival or recurrence risk, it could be because the women in the study didn't meet the targets for vegetable and fiber consumption or fat reduction.
More research is needed in this important area for women who are interested in eating well to reduce their risk of ever getting breast cancer or the breast cancer coming back.
In the meantime, here's what dietitians suggest:
Keep your body weight in a healthy range for your height and frame. Body mass index, though not a perfect measurement, can help you estimate your healthy weight.
Eat plenty of vegetables and fruit (more than five cups a day).
Try to limit your fat intake to less than 20% of your total calories per day. This is an extremely small amount of fat to eat (an average amount is about 30 to 35% of total calories per day). Start by eliminating some foods with the highest fat content (like fried foods and margarine) and gradually lower the amount of fat you eat.
Eat foods high in omega-3 fatty acids.
Avoid trans fats, red meats, and charred or smoked foods.
You'll find that processed foods generally don't fit in this type of diet as well as fresh foods do.
To develop a healthy diet that meets your needs, seek advice from a registered dietitian. He or she will thoroughly evaluate your medical, diet, and weight history. Then the registered dietitian will work with you on an individualized plan to meet all your goals:
keep your risk of breast cancer as low as possible
provide you with good nutrition
keep you as healthy as possible
Nutrition and Cancer
The overall result of these experiments (described in the research paper from the journal Mechanisms of Ageing and Development reproduced in pdf format below) on squamous cell carcinoma in mice is that healthful diets increase the growth rate of cancer. Poor diets decrease its growth rate. This is probably a general effect that applies equally well to humans.
While it is likely (although not proved) that excellent nutrition strengthens the immune system and other defense mechanisms in such a way as to lower the probability of contracting cancer, it is clear that, once cancer has established itself, excellent nutrition leads to its accelerated growth. This may not be true of all cancers, but it is likely to be true of a large fraction of them.
The attempts to develop drugs that decrease the vascularization of hard tumors have been well publicized. These are essentially efforts to reduce the nutrients supplied to the cancer tissue itself, while not affecting the rest of the body. While a promising area of research, these drugs are not now available.
We discovered, however, that starving the whole organism is very effective in mice. (There are many anecdotal accounts of this in humans, also, but no controlled trials.)
The growth rate of cancer in these mice was varied over a 20-fold range by diet alone. Super nutrition (lots of vitamins, etc.) increased the growth rate two-fold, while diet restriction reduced the growth rate ten-fold.
Although this was done with one organism (mice) and with one cancer (squamous cell carcinoma), the effect is so large that it is very likely that it will be seen in humans and with other types of cancer. Also, the rationale for its effect is simple and sensible, and many individual humans have experienced this effect.
There are numerous ways to reduce one's nutritional intake. Perhaps the safest and most enjoyable (and highest quality for the nutrients that are ingested) is the raw fruits and vegetable diet originally developed by Ann Wigmore (now deceased) and her co-workers. This was popularized by Arn and Edie Mae Hunsberger in their book, "How I Conquered Cancer Naturally." (The book is still available through the link at the bottom of this page.) These developers and writers did not understand why their diet helped cancer victims and tended to give explanations based on improved nutrition.
It is a fact, however, that one cannot obtain sufficient nutrients (over a prolonged period) from raw fruits and vegetables alone because the bulk fiber and water in these diets prevents eating enough. The proponents advocated juicing (to get more) and supplements of staples after a month or two. They also, in later years, added staples to the diets initially.
Note that, in the mouse experiments on raw fruits and vegetables, the cancer slowing effect was completely lost when soy protein or other dietary improvements were added.
Cancer is a scourge that afflicts hundreds of millions of people. Hopefully, someday there will be a completely effective ordinary therapy. In the meantime, however, if I or some other member of my family contracted cancer, we would make the best guess possible as to the proper response. In that case, we would definitely choose diet restriction by raw fruits and vegetables in accordance with the research shown here.
One final note, describing one of many human stories that I have heard over the years:
A surgeon telephoned me to ask some questions about this diet. During the conversation, he told me why he had become interested in it (to the great displeasure of his colleagues).
A patient had come to him in whose throat was growing a completely inoperable and soon-to-be-fatal cancer. He told the patient that there was nothing he could do for him and that he would soon die.
The patient, however, went to Ann Wigmore's establishment and started eating their initial diet of strictly raw fruits and vegetables. He pursued this fanatically, however, and never switched to Wigmore and Hunsberger's phase-two diet including additional staples.
Many months later, the patient returned to the surgeon. The surgeon told me that there were three things that were unusual about this patient.
1. He was back. He should already have been long dead.
2. There was not a trace of cancer in his throat.
3. He looked like he had just stepped out of a Nazi or Communist concentration camp. The patient was almost dead of malnutrition. He was a walking skeleton.
The surgeon nursed him back to good nutritional health - but the cancer never returned.
All of our experiments on diet restriction involved slowing the growth rate of cancer (although slowing by 20-fold is equivalent to a cure in people of advanced age). We did not observe cures or remissions of the cancer. It is possible that this occurred with some mice, but we were not specifically studying it.
Therefore, I am not willing to say that diet restriction will cause the remission of tumors. I know, however, that diet restriction can slow the growth of cancer markedly. This effect is so large that, in my opinion, if diet restriction were practiced by all cancer patients in the United States, the resulting life-extension might equal or surpass that resulting from the combined efforts of the entire current medical oncology effort.
The research paper reproduced in pdf format below summarizes work carried out by my coworkers and me when I was President and Research Director of the Linus Pauling Institute of Science and Medicine. The results of these experiments caused an argument between Linus and me, which ended our 16-year period of work together. He was not willing to accept the experimentally proved fact that vitamin C in ordinary doses accelerated the growth rate of squamous cell carcinoma in these mice. At the time, Linus was promoting his claim that "75% of all cancer can be prevented and cured by vitamin C alone." This claim proved to be without experimental foundation and not true, although the possibility that modest doses of vitamin C somewhat improve resistance to cancer has never been adequately tested. The dose response curve of vitamin C vs. mouse squamous cell carcinoma is shown in the paper below. Vitamin C increased the rate of growth of cancer at human equivalents of 1 to 5 grams per day, but suppressed the cancer growth rate at doses on the order of 100 grams per day (near the lethal dose), as do other measures of malnutrition
While it is likely (although not proved) that excellent nutrition strengthens the immune system and other defense mechanisms in such a way as to lower the probability of contracting cancer, it is clear that, once cancer has established itself, excellent nutrition leads to its accelerated growth. This may not be true of all cancers, but it is likely to be true of a large fraction of them.
The attempts to develop drugs that decrease the vascularization of hard tumors have been well publicized. These are essentially efforts to reduce the nutrients supplied to the cancer tissue itself, while not affecting the rest of the body. While a promising area of research, these drugs are not now available.
We discovered, however, that starving the whole organism is very effective in mice. (There are many anecdotal accounts of this in humans, also, but no controlled trials.)
The growth rate of cancer in these mice was varied over a 20-fold range by diet alone. Super nutrition (lots of vitamins, etc.) increased the growth rate two-fold, while diet restriction reduced the growth rate ten-fold.
Although this was done with one organism (mice) and with one cancer (squamous cell carcinoma), the effect is so large that it is very likely that it will be seen in humans and with other types of cancer. Also, the rationale for its effect is simple and sensible, and many individual humans have experienced this effect.
There are numerous ways to reduce one's nutritional intake. Perhaps the safest and most enjoyable (and highest quality for the nutrients that are ingested) is the raw fruits and vegetable diet originally developed by Ann Wigmore (now deceased) and her co-workers. This was popularized by Arn and Edie Mae Hunsberger in their book, "How I Conquered Cancer Naturally." (The book is still available through the link at the bottom of this page.) These developers and writers did not understand why their diet helped cancer victims and tended to give explanations based on improved nutrition.
It is a fact, however, that one cannot obtain sufficient nutrients (over a prolonged period) from raw fruits and vegetables alone because the bulk fiber and water in these diets prevents eating enough. The proponents advocated juicing (to get more) and supplements of staples after a month or two. They also, in later years, added staples to the diets initially.
Note that, in the mouse experiments on raw fruits and vegetables, the cancer slowing effect was completely lost when soy protein or other dietary improvements were added.
Cancer is a scourge that afflicts hundreds of millions of people. Hopefully, someday there will be a completely effective ordinary therapy. In the meantime, however, if I or some other member of my family contracted cancer, we would make the best guess possible as to the proper response. In that case, we would definitely choose diet restriction by raw fruits and vegetables in accordance with the research shown here.
One final note, describing one of many human stories that I have heard over the years:
A surgeon telephoned me to ask some questions about this diet. During the conversation, he told me why he had become interested in it (to the great displeasure of his colleagues).
A patient had come to him in whose throat was growing a completely inoperable and soon-to-be-fatal cancer. He told the patient that there was nothing he could do for him and that he would soon die.
The patient, however, went to Ann Wigmore's establishment and started eating their initial diet of strictly raw fruits and vegetables. He pursued this fanatically, however, and never switched to Wigmore and Hunsberger's phase-two diet including additional staples.
Many months later, the patient returned to the surgeon. The surgeon told me that there were three things that were unusual about this patient.
1. He was back. He should already have been long dead.
2. There was not a trace of cancer in his throat.
3. He looked like he had just stepped out of a Nazi or Communist concentration camp. The patient was almost dead of malnutrition. He was a walking skeleton.
The surgeon nursed him back to good nutritional health - but the cancer never returned.
All of our experiments on diet restriction involved slowing the growth rate of cancer (although slowing by 20-fold is equivalent to a cure in people of advanced age). We did not observe cures or remissions of the cancer. It is possible that this occurred with some mice, but we were not specifically studying it.
Therefore, I am not willing to say that diet restriction will cause the remission of tumors. I know, however, that diet restriction can slow the growth of cancer markedly. This effect is so large that, in my opinion, if diet restriction were practiced by all cancer patients in the United States, the resulting life-extension might equal or surpass that resulting from the combined efforts of the entire current medical oncology effort.
The research paper reproduced in pdf format below summarizes work carried out by my coworkers and me when I was President and Research Director of the Linus Pauling Institute of Science and Medicine. The results of these experiments caused an argument between Linus and me, which ended our 16-year period of work together. He was not willing to accept the experimentally proved fact that vitamin C in ordinary doses accelerated the growth rate of squamous cell carcinoma in these mice. At the time, Linus was promoting his claim that "75% of all cancer can be prevented and cured by vitamin C alone." This claim proved to be without experimental foundation and not true, although the possibility that modest doses of vitamin C somewhat improve resistance to cancer has never been adequately tested. The dose response curve of vitamin C vs. mouse squamous cell carcinoma is shown in the paper below. Vitamin C increased the rate of growth of cancer at human equivalents of 1 to 5 grams per day, but suppressed the cancer growth rate at doses on the order of 100 grams per day (near the lethal dose), as do other measures of malnutrition
DO FRUITS AND VEGETABLES PROTECT AGAINST BOWEL CANCER
Most studies suggest they do to at least a moderate extent - particularly vegetables. But, two studies reported together in the November 1, 2000 issue of the Journal of the National Cancer Institute find no benefit at all. The Nurses’ Health Study and the Health Professionals Study together followed about 135,000 women and men over a period of ten to sixteen years during which time 1,181 cases of bowel cancer occurred. So, it is a very large study. The investigators found absolutely no benefit from even as much as six or more servings of fruits and vegetables in the daily diet.
The authors acknowledge that between two-thirds and three-quarters of other studies do show reduced risk from eating more fruits and vegetables as a group or from specific vegetables, but they argue theirs are particularly good studies that are supported by other good studies.
They conclude "high consumption of fruit and vegetables did not appear to be protective against cancers of the colon or rectum in our large U.S. cohort".
Commentary: These are well-conducted studies by good investigators. Does this mean that including six to eight or more portions of fruits and vegetables in your daily diet is definitely useless in helping prevent bowel cancer? The answer is absolutely not.
Many other studies do find evidence that vegetables (more than fruits) reduce the risk of bowel cancer. Additionally, these investigators have published the results of a study on the same subjects saying folic acid reduces bowel cancer risk. Fruits and vegetables are a very good source of folic acid. To get around that apparent contradiction, the authors say that other sources of folic acid, including vitamin supplements, are more important sources than fruits and vegetables. They may well be correct, but the apparent contradiction with their own previously published study is still a bit disturbing.
At present, in part because of the weakness of the Food and Drug Administration, the public is going to be deluged by claims of health promotion-disease prevention for specific foods, particularly fruits and vegetables. Most of those claims are exaggerations and are inadequately documented.
This article, among others, tells us we had better be cautious about claims relating to health benefits of fruits and vegetables. For example, the claim is made that one-third of the overall cancer (and one-half or more of the risk for bowel, breast, and prostate cancer) risk can be ascribed to diet. That claim is, at present, inadequately documented.
Nevertheless, fruits and vegetables, if taken in good amounts (at least four to six servings of fruits and vegetables combined each day) do appear to offer modest protection against some cancers, coronary heart disease, and stroke.
Multiple servings a day of fruits and vegetables should be part of the prudent diet; whether they specifically reduce the risk of bowel cancer is not clear.
The authors acknowledge that between two-thirds and three-quarters of other studies do show reduced risk from eating more fruits and vegetables as a group or from specific vegetables, but they argue theirs are particularly good studies that are supported by other good studies.
They conclude "high consumption of fruit and vegetables did not appear to be protective against cancers of the colon or rectum in our large U.S. cohort".
Commentary: These are well-conducted studies by good investigators. Does this mean that including six to eight or more portions of fruits and vegetables in your daily diet is definitely useless in helping prevent bowel cancer? The answer is absolutely not.
Many other studies do find evidence that vegetables (more than fruits) reduce the risk of bowel cancer. Additionally, these investigators have published the results of a study on the same subjects saying folic acid reduces bowel cancer risk. Fruits and vegetables are a very good source of folic acid. To get around that apparent contradiction, the authors say that other sources of folic acid, including vitamin supplements, are more important sources than fruits and vegetables. They may well be correct, but the apparent contradiction with their own previously published study is still a bit disturbing.
At present, in part because of the weakness of the Food and Drug Administration, the public is going to be deluged by claims of health promotion-disease prevention for specific foods, particularly fruits and vegetables. Most of those claims are exaggerations and are inadequately documented.
This article, among others, tells us we had better be cautious about claims relating to health benefits of fruits and vegetables. For example, the claim is made that one-third of the overall cancer (and one-half or more of the risk for bowel, breast, and prostate cancer) risk can be ascribed to diet. That claim is, at present, inadequately documented.
Nevertheless, fruits and vegetables, if taken in good amounts (at least four to six servings of fruits and vegetables combined each day) do appear to offer modest protection against some cancers, coronary heart disease, and stroke.
Multiple servings a day of fruits and vegetables should be part of the prudent diet; whether they specifically reduce the risk of bowel cancer is not clear.
What It Means:
Based on the results of this analysis of research studies, it appears that, like other forms of cancer, one way to reduce your risk of mouth cancer is to include more fruits and vegetables in your daily diet. Even if your current intake is low, adding just one additional serving each day can significantly impact your health and cut your risk in half.
This research adds to the vast array of research illustrating numerious benefits of eating more fruits and vegetables. Other studies show that a high intake of fruit and vegetables is linked to lower risk of heart disease, stroke, high blood pressure, obesity, and decreased risk of death from all causes.
This research adds to the vast array of research illustrating numerious benefits of eating more fruits and vegetables. Other studies show that a high intake of fruit and vegetables is linked to lower risk of heart disease, stroke, high blood pressure, obesity, and decreased risk of death from all causes.
Fruits and Vegetables Protect Against Oral Cancer
Oral cancer is a major cause of cancer both in the United States and worldwide with 29,000 and 400,000 new cases respectively each year. This type of cancer has a high mortality rate. Therefore, prevention is the best strategy at fighting this disease.
Researchers analyzed data from 16 studies on mouth cancer and found that a higher intake of fruits and vegetables is protective against developing mouth cancer. Both fruit and vegetable intake were examined independently and were both found to be significantly related to a lower cancer risk.
Each additional serving of fruit showed a 49% decreased risk of developing mouth cancer compared to people eating an average fruit intake. Similarly, each additional serving of vegetables showed a 50% reduction in mouth cancer. These reductions in risk were found after adjusting for other risk factors such as smoking or alcohol intake.
Citrus fruits were found to be most closely related to lower risk of cancer; it was found that an additional serving (above the average intake) of citrus fruit daily resulted in a 62% decrease in oral cancer risk. Other lifestyles linked to higher risk of oral cancer include: smoking, regular alcohol intake, and in countries were common, betel quid chewing.
Researchers analyzed data from 16 studies on mouth cancer and found that a higher intake of fruits and vegetables is protective against developing mouth cancer. Both fruit and vegetable intake were examined independently and were both found to be significantly related to a lower cancer risk.
Each additional serving of fruit showed a 49% decreased risk of developing mouth cancer compared to people eating an average fruit intake. Similarly, each additional serving of vegetables showed a 50% reduction in mouth cancer. These reductions in risk were found after adjusting for other risk factors such as smoking or alcohol intake.
Citrus fruits were found to be most closely related to lower risk of cancer; it was found that an additional serving (above the average intake) of citrus fruit daily resulted in a 62% decrease in oral cancer risk. Other lifestyles linked to higher risk of oral cancer include: smoking, regular alcohol intake, and in countries were common, betel quid chewing.
The Bottom Line: Recommendations for Fruit and Vegetable Intake
Fruits and vegetables are clearly an important part of a good diet. Almost everyone can benefit from eating more of them, but variety is as important as quantity. No single fruit or vegetable provides all of the nutrients you need to be healthy. The key lies in the variety of different fruits and vegetables that you eat.
Some basic fruit and vegetable tips:
Try to eat more fruits and vegetables. If you need 2,000 calories a day to maintain your weight and health, aim for at least nine servings (4½ cups) a day.
Choose a variety of different fruits and vegetables. It's easy to get into a rut when it comes to the food you eat. Break out and try a wider variety - include dark-green, leafy vegetables; yellow, orange, and red fruits and vegetables; cooked tomatoes; and citrus fruits.
Some basic fruit and vegetable tips:
Try to eat more fruits and vegetables. If you need 2,000 calories a day to maintain your weight and health, aim for at least nine servings (4½ cups) a day.
Choose a variety of different fruits and vegetables. It's easy to get into a rut when it comes to the food you eat. Break out and try a wider variety - include dark-green, leafy vegetables; yellow, orange, and red fruits and vegetables; cooked tomatoes; and citrus fruits.
Fruits, Vegetables, and Vision
Eating plenty of fruits and vegetables also keeps your eyes in good shape. You may have learned that the vitamin A in carrots aids night vision. Other fruits and vegetables help prevent two common aging-related eye diseases - cataract and macular degeneration - which afflict millions of Americans over age sixty-five. Cataract is the gradual clouding of the eye's lens, a disk of protein that focuses light on the light-sensitive retina. Macular degeneration is caused by cumulative damage to the macula, the center of the retina. It starts as a blurred spot in the center of what you see. As the degeneration spreads, vision shrinks.
Free radicals generated by sunlight, cigarette smoke, air pollution, infection, and metabolism cause much of this damage. Dark green leafy vegetables contain two pigments, lutein and zeaxanthin, that accumulate in the eye. These two appear to be able to snuff out free radicals before they can harm the eye's sensitive tissues.(12)
In general, a diet rich in fruits, vegetables, and whole grains appears to reduce the chances of developing cataract or macular degeneration. (13-15)
Free radicals generated by sunlight, cigarette smoke, air pollution, infection, and metabolism cause much of this damage. Dark green leafy vegetables contain two pigments, lutein and zeaxanthin, that accumulate in the eye. These two appear to be able to snuff out free radicals before they can harm the eye's sensitive tissues.(12)
In general, a diet rich in fruits, vegetables, and whole grains appears to reduce the chances of developing cataract or macular degeneration. (13-15)
Fruits, Vegetables, and Cancer
Numerous early studies revealed what appeared to be a strong link between eating fruits and vegetables and protection against cancer. But because many of these were case-control studies, it is possible that the results may have been skewed by problems inherent in these types of studies, such as recall bias and selection bias. Data from cohort studies that follow large groups of initially healthy individuals for years have not consistently shown that a diet rich in fruits and vegetables prevents cancer in general. Data from the Nurses' Health Study and Health Professionals Follow-up Study support this finding. Over a 14-year period, men and women with the highest intake of fruits and vegetables (8+ servings a day) were just as likely to have developed cancer as those who ate the fewest daily servings (under 1.5).(2)
A more likely possibility is that fruits and vegetables may protect against certain cancers. The International Agency for Research on Cancer, which is part of the World Health Organization, recently completed a monumental review of the best research on fruits, vegetables, and cancer. Here's what this 387-page tome concludes about studies in humans: "There is limited evidence for a cancer-preventive effect of consumption of fruit and of vegetables for cancers of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of consumption of fruit and of vegetables for all other sites." (5) However, considering all evidence from human epidemiological, animal, and other types of studies, it appears that eating more fruit "probably lowers the risk of cancers of the esophagus, stomach and lung" and "possibly reduces the risk of cancers of the mouth, pharynx, colon-rectum, larynx, kidney, and urinary bladder." Eating more vegetables "probably lowers the risk of cancers of the esophagus and colon-rectum" and "possibly reduces the risk of cancers of the mouth, pharynx, stomach, larynx, lung, ovary and kidney."
Keep in mind that this is for total fruit and total vegetable consumption and that, as pointed out by the International Agency for Research on Cancer, specific fruits and vegetables may protect against specific types of cancer. For example, a line of research stemming from a finding from the Health Professionals Follow-up Study suggest that tomatoes may help protect men against prostate cancer, especially aggressive forms of it. (6-8) One of the pigments that give tomatoes their red hue - lycopene - could be involved in this protective effect. Although several studies other than the Health Professionals' study have also demonstrated a link between tomatoes or lycopene and prostate cancer, others have not or have found only a weak connection. Taken as a whole, however, these studies suggest that increased consumption of tomato-based products (especially cooked tomato products) and other lycopene-containing foods may reduce the occurrence or progression of prostate cancer. But more research is needed before we know the exact relationship between fruits and vegetables, carotenoids, and prostate cancer.(9)
A more likely possibility is that fruits and vegetables may protect against certain cancers. The International Agency for Research on Cancer, which is part of the World Health Organization, recently completed a monumental review of the best research on fruits, vegetables, and cancer. Here's what this 387-page tome concludes about studies in humans: "There is limited evidence for a cancer-preventive effect of consumption of fruit and of vegetables for cancers of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of consumption of fruit and of vegetables for all other sites." (5) However, considering all evidence from human epidemiological, animal, and other types of studies, it appears that eating more fruit "probably lowers the risk of cancers of the esophagus, stomach and lung" and "possibly reduces the risk of cancers of the mouth, pharynx, colon-rectum, larynx, kidney, and urinary bladder." Eating more vegetables "probably lowers the risk of cancers of the esophagus and colon-rectum" and "possibly reduces the risk of cancers of the mouth, pharynx, stomach, larynx, lung, ovary and kidney."
Keep in mind that this is for total fruit and total vegetable consumption and that, as pointed out by the International Agency for Research on Cancer, specific fruits and vegetables may protect against specific types of cancer. For example, a line of research stemming from a finding from the Health Professionals Follow-up Study suggest that tomatoes may help protect men against prostate cancer, especially aggressive forms of it. (6-8) One of the pigments that give tomatoes their red hue - lycopene - could be involved in this protective effect. Although several studies other than the Health Professionals' study have also demonstrated a link between tomatoes or lycopene and prostate cancer, others have not or have found only a weak connection. Taken as a whole, however, these studies suggest that increased consumption of tomato-based products (especially cooked tomato products) and other lycopene-containing foods may reduce the occurrence or progression of prostate cancer. But more research is needed before we know the exact relationship between fruits and vegetables, carotenoids, and prostate cancer.(9)
Fruits and Vegetables, Blood Pressure, and Cholesterol
High blood pressure is a primary risk factor for heart disease and stroke. As such, it's a condition that is very important to control. Diet can be a very effective tool for lowering blood pressure. One of the most convincing associations between diet and blood pressure was found in the Dietary Approaches to Stop Hypertension (DASH) study. (3) This trial examined the effect on blood pressure of a diet that was rich in fruits, vegetables, and low-fat dairy products and that restricted the amount of saturated and total fat. The researchers found that people with high blood pressure who followed this diet reduced their systolic blood pressure (the upper number of a blood pressure reading) by about 11 mm Hg and their diastolic blood pressure (the lower number) by almost 6 mm Hg - as much as medications can achieve.
Eating more fruits and vegetables can also help lower cholesterol. In the National Heart, Lung, and Blood Institute's Family Heart Study, the 4466 subjects consumed on average a shade over 3 servings of fruits and vegetables a day. Men and women with the highest daily consumption (more than 4 servings a day) had significantly lower levels of LDL (bad) cholesterol than those with lower consumption.(4) How fruits and vegetables lower cholesterol is still something of a mystery. It is possible that eating more fruits and vegetables means eating less meat and dairy products, and thus less cholesterol-boosting saturated fat. Soluble fiber in fruits and vegetables may also block the absorption of cholesterol from food.
Eating more fruits and vegetables can also help lower cholesterol. In the National Heart, Lung, and Blood Institute's Family Heart Study, the 4466 subjects consumed on average a shade over 3 servings of fruits and vegetables a day. Men and women with the highest daily consumption (more than 4 servings a day) had significantly lower levels of LDL (bad) cholesterol than those with lower consumption.(4) How fruits and vegetables lower cholesterol is still something of a mystery. It is possible that eating more fruits and vegetables means eating less meat and dairy products, and thus less cholesterol-boosting saturated fat. Soluble fiber in fruits and vegetables may also block the absorption of cholesterol from food.
Fruits, Vegetables, and Cardiovascular Disease
There is compelling evidence that a diet rich in fruits and vegetables can lower the risk of heart disease and stroke.
The largest and longest study to date, done as part of the Harvard-based Nurses' Health Study and Health Professionals Follow-up Study, included almost 110,000 men and women whose health and dietary habits were followed for 14 years. The higher the average daily intake of fruits and vegetables, the lower the chances of developing cardiovascular disease. Compared with those in the lowest category of fruit and vegetable intake (less than 1.5 servings a day), those who averaged 8 or more servings a day were 30% less likely to have had a heart attack or stroke.(2)
Although all fruits and vegetables likely contribute to this benefit, green leafy vegetables such as lettuce, spinach, Swiss chard, and mustard greens; cruciferous vegetables such as broccoli, cauliflower, cabbage, Brussels sprouts, bok choy, and kale; and citrus fruits such as oranges, lemons, limes, and grapefruit (and their juices) make important contributions.
The largest and longest study to date, done as part of the Harvard-based Nurses' Health Study and Health Professionals Follow-up Study, included almost 110,000 men and women whose health and dietary habits were followed for 14 years. The higher the average daily intake of fruits and vegetables, the lower the chances of developing cardiovascular disease. Compared with those in the lowest category of fruit and vegetable intake (less than 1.5 servings a day), those who averaged 8 or more servings a day were 30% less likely to have had a heart attack or stroke.(2)
Although all fruits and vegetables likely contribute to this benefit, green leafy vegetables such as lettuce, spinach, Swiss chard, and mustard greens; cruciferous vegetables such as broccoli, cauliflower, cabbage, Brussels sprouts, bok choy, and kale; and citrus fruits such as oranges, lemons, limes, and grapefruit (and their juices) make important contributions.
fruits and vegetables
"Eat your fruits and vegetables" is one of the tried and true recommendations for a healthy diet. And for good reason. Eating plenty of fruits and vegetables can help you ward off heart disease and stroke, control blood pressure and cholesterol, prevent some types of cancer, avoid a painful intestinal ailment called diverticulitis, and guard against cataract and macular degeneration, two common causes of vision loss.
What does "plenty" mean? More than most Americans consume. If you don't count potatoes - which should be considered a starch rather than a vegetable - the average American gets a total of just three servings of fruits and vegetables a day. The latest dietary guidelines call for five to thirteen servings of fruits and vegetables a day, depending on one's caloric intake.(1) For a person who needs 2,000 calories a day to maintain weight and health, this translates into nine servings, or 4½ cups per day.
Over the past 30 years or so, researchers have developed a solid base of science to back up what generations of mothers preached (but didn't always practice themselves). Early on, fruits and vegetables were acclaimed as cancer-fighting foods. In fact, the ubiquitous 5-A-Day message (now quietly changing to Eat 5 to 9 A Day) seen in produce aisles, magazine ads, and schools is supported in part by the National Cancer Institute. The latest research, though, suggests that the biggest payoff from eating fruits and vegetables is for the heart.
What does "plenty" mean? More than most Americans consume. If you don't count potatoes - which should be considered a starch rather than a vegetable - the average American gets a total of just three servings of fruits and vegetables a day. The latest dietary guidelines call for five to thirteen servings of fruits and vegetables a day, depending on one's caloric intake.(1) For a person who needs 2,000 calories a day to maintain weight and health, this translates into nine servings, or 4½ cups per day.
Over the past 30 years or so, researchers have developed a solid base of science to back up what generations of mothers preached (but didn't always practice themselves). Early on, fruits and vegetables were acclaimed as cancer-fighting foods. In fact, the ubiquitous 5-A-Day message (now quietly changing to Eat 5 to 9 A Day) seen in produce aisles, magazine ads, and schools is supported in part by the National Cancer Institute. The latest research, though, suggests that the biggest payoff from eating fruits and vegetables is for the heart.
Benefit for Specific Cancers Possible
Another possibility, Calle said, is that the study masked any protective effect on cancer by looking at all cancers combined, rather than specific cancers.
"Cancers are very different from one another, and risk factors for cancer are very different," she said. "If you looked at individual cancers you might see things that you don't see with all cancers combined."
Willett also noted that some fruits and vegetables may have an effect on some types of cancer.
"I think it is plausible that there are some components of fruits and vegetables that may modestly reduce the risk of some cancers, but lumping all fruits and vegetables together obscures the benefit," he said. "For example, we have seen evidence that a higher intake of tomato-based products may reduce the risk of prostate cancer."
In addition, the researchers found a protective association for cruciferous vegetables (such as cauliflower, cabbage, broccoli, and even mustard and collard greens, for instance) and cancer, but only in men. Whether the types of cancers occurring in men are more responsive to these types of vegetables compared to cancers in women remains to be determined.
The bottom line, Calle said, is that studying the effects of foods on disease is a very complex process. "While the data don't really indicate a reduction in risk for all cancers combined, we're not really ready to believe there's no reduction for individual cancer sites," she said. "Fruits and vegetables are healthy choices whether we can directly show this impact on all cancers combined or not."
"Cancers are very different from one another, and risk factors for cancer are very different," she said. "If you looked at individual cancers you might see things that you don't see with all cancers combined."
Willett also noted that some fruits and vegetables may have an effect on some types of cancer.
"I think it is plausible that there are some components of fruits and vegetables that may modestly reduce the risk of some cancers, but lumping all fruits and vegetables together obscures the benefit," he said. "For example, we have seen evidence that a higher intake of tomato-based products may reduce the risk of prostate cancer."
In addition, the researchers found a protective association for cruciferous vegetables (such as cauliflower, cabbage, broccoli, and even mustard and collard greens, for instance) and cancer, but only in men. Whether the types of cancers occurring in men are more responsive to these types of vegetables compared to cancers in women remains to be determined.
The bottom line, Calle said, is that studying the effects of foods on disease is a very complex process. "While the data don't really indicate a reduction in risk for all cancers combined, we're not really ready to believe there's no reduction for individual cancer sites," she said. "Fruits and vegetables are healthy choices whether we can directly show this impact on all cancers combined or not."
Study Methods May Affect Results
Why didn't Willett's study show a bigger impact on cancer from these healthy foods? There could be a number of reasons.
One possibility raised in an editorial accompanying the study is that the food questionnaires used to gauge people's diets may not be entirely accurate. In this study, as in many others, participants were asked how often they had eaten particular foods over the past year; if their recollections were flawed, the study results may be, too.
If that's the case, then it's possible that the protective effect on cardiovascular disease is even greater than the study showed, and that there actually is an effect on cancer that the study couldn't find.
The time frame of the study may also have disguised an effect of fruits and veggies on cancer risk. Because cancer can take decades to develop, it may simply take longer follow-up to find a benefit.
Or, Calle said, it may be that what people ate more recently has more of an impact on heart disease, while diet at a younger age has more of an impact on cancer. The Harvard researchers only tracked what participants ate during the course of the study, not during earlier periods of life.
One possibility raised in an editorial accompanying the study is that the food questionnaires used to gauge people's diets may not be entirely accurate. In this study, as in many others, participants were asked how often they had eaten particular foods over the past year; if their recollections were flawed, the study results may be, too.
If that's the case, then it's possible that the protective effect on cardiovascular disease is even greater than the study showed, and that there actually is an effect on cancer that the study couldn't find.
The time frame of the study may also have disguised an effect of fruits and veggies on cancer risk. Because cancer can take decades to develop, it may simply take longer follow-up to find a benefit.
Or, Calle said, it may be that what people ate more recently has more of an impact on heart disease, while diet at a younger age has more of an impact on cancer. The Harvard researchers only tracked what participants ate during the course of the study, not during earlier periods of life.
Food Only One Part of the Equation
The Harvard study, published in the Journal of the National Cancer Institute (Vol. 96, No. 21:1577-1584), followed more than 100,000 participants for more than 10 years, periodically asking them what they ate and whether they had developed cancer, or had a stroke or heart attack.
Its findings support the 5-a-day recommendation, said senior author Walter Willett, MD.
"Our study means that everyone should still try to eat 5 or more servings of fruit and vegetables per day, but that the benefit will be mainly for cardiovascular disease," he said.
It's possible that fruits and vegetables do protect against cancer, he said, but the benefit is not as great as the public may believe. "Not smoking, avoiding [becoming] overweight, and staying physically active will be more effective in preventing cancer."
Its findings support the 5-a-day recommendation, said senior author Walter Willett, MD.
"Our study means that everyone should still try to eat 5 or more servings of fruit and vegetables per day, but that the benefit will be mainly for cardiovascular disease," he said.
It's possible that fruits and vegetables do protect against cancer, he said, but the benefit is not as great as the public may believe. "Not smoking, avoiding [becoming] overweight, and staying physically active will be more effective in preventing cancer."
Do Fruits and Veggies Protect Against Cancer
A new study suggests eating fruits and vegetables does more to prevent heart disease than cancer. Researchers at the Harvard School of Public Health found that people who ate at least 5 servings a day of fruits and vegetables had a 28% lower risk of heart disease than people who ate less than 1.5 servings per day. Cancer risk, however, was not affected by the amount of fruits and vegetables eaten
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