There's too much information about what we should eat as survivors. However, many messages remain pretty consistent across sources. We should eat at least 5 portions of fruit and non-starchy vegetables daily. One serving of fruit is approximately 1 medium apple, 1/2 cup of juice or chopped up or canned fruit. One serving of vegetables is 1 cup of raw leafy greens and 1/2 cup of other vegetables. Although studies haven't clearly demonstrated a survival benefit in all patients who follow these recommendations, there is a reduction in other diseases that become a problem with breast cancer survivors and weight gain. Please see a comprehensive review by Dieli-Conwright, et al. Most doctors will tell you that getting your 5 fruits and vegetables is more important than forgoing them if you can't afford organic. However, I do refer to the Environmental Working Group's "Dirty Dozen" list when buying produce. In addition to fruit and vegetables, we should consume 3 servings of whole grains or legumes/beans daily and up to 3 weekly servings of fish.
There is also an interesting site called Foodforbreastcancer.com that contains a list of foods which may reduce recurrence as well as links to data. Unfortunately, most of the studies are in vitro (meaning they were performed in a lab with cultured breast cells). Once the cells are in the micro and macro environment of the human body, they can and do behave very differently. Therefore, doctors are hesitant to make recommendations based solely upon in vitro studies.
WHAT'S NEW WITH MEAT? Is science starting to explain why meat restriction is beneficial?
There's a big push for becoming a vegetarian in many cancer cookbooks and internet sites. The latest suggestion is that a diet low in methionine may reduce recurrence. Methionine is one of eight essential amino acid and is used for the production of homocysteine, cysteine, taurine, S-adenosyl methionine (SAMe) and polyamides. It is present in large amounts in red meat and meat in general. Dr. Lamb and others found that methionine deprivation reduced growth of tumor-initiating cells (TICs- stem cells) in vitro. Please see Targeting tumor-initiating cells: eliminating anabolic cancer stem cells with inhibitors of protein synthesis or by mimicking caloric restriction. Oncotarget. 2015;6(7):4585-4601NaturalHealth365small study on cancer patientsstudyThe Role of Methionine in Cancer Growth and Control. Methionine deprivation also caused an increase in TNF-related apoptosis-inducing ligand receptor-2 (TRAIL-R2) mRNA with in cultured TNBC cells. Tina Kaczor, a naturopathic oncologist, provides a nice summary of of the role of methionine depletion in cancer cells and summarizes human studies that are currently available. She suggests that caloric restriction, intermittent fasting, and the vegetarian diet may reduce protein synthesis in TICs.
In the future, nutritional methionine depletion and the use of methioninase may be used with chemotherapeutic regimens. However, general protein restriction may still be moremethion beneficial than methionine restriction alone.
A methionine restrictive diet may not be possible to follow, especially at the levels used in human studies (2mg/kg body weight). I weigh 125lbs or 57kg. Therefore, I could only eat 114mg of methionine per day. There are many online references for methionine content in food. Some sites include: nutritiondata.self.com and morelife.org.
I follow general oncological recommendations such as those by Johns Hopkins, which are based on extensive research. Namely, to reduce red meat and control portions of other types of meats (except seafood, in which 3 or more weekly servings are recommended). According to the National Institutes of Health-AARP study that was based on the dietary recall of more than a half-million elderly Americans, those who ate about 4 ounces of red meat per day were more likely to die of cancer or heart disease than those who ate less than half an ounce per day. Half an ounce of meat daily would be in line with a low-methionine diet! I believe that intermittent fasting and caloric restriction may also be beneficial. Of interest, red meat also reduces levels of melatonin (see my blog), which can result in insomnia!
It appears that pescovegetarians (those vegetarians who eat fish) may reap the greatest benefit from cancer protection. Please see Dr. Mercola's article referring to a recent publication in JAMA. Pescovegetarians had a 42% reduction in developing colon cancer when compared to non-vegetarians and a 27% reduced risk compared to vegetarians. See the May 2015 article from JAMA. There are many studies that demonstrate the benefits of fish consumption and cancer. Please also see references 9-29 in the article by Fernandez et al. in the American Journal of Clinical Nutrition. However, there are also recent studies that show just the opposite. Take prostate cancer, for example. In the SELECT trial (Selenium and Vitamin E Cancer prevention Trial), a sub-cohort of over 800 men had blood levels of omega-3 fatty acids tested and those in the highest quartile had a greater risk for developing prostate cancer.
Some studies suggest that fish oils can interfere with immunity, which is often paramount to fighting cancer.
My take on all of this is that in regards to fish supplementation and omega-3 fatty acids, we just don't know. Therefore, I currently do not take omega-3 supplements but do enrich my diet with wild caught fish occasionally (not necessarily 3 times per week) as it provides many nutrients in addition to omega-3 fatty acids and Vitamin D. Maybe there's a sweet spot, where just enough if beneficial but too much is detrimental. Vegetarians must supplement their diets with B12 and plant-based proteins. Any dietary change should be made under the supervision of your physician and/or a dietician.
*Please discuss any dietary changes with your oncologist first. If you are having trouble maintaining your weight, excluding foods from your diet may not be appropriate. Most of my blogs address lifestyle changes that may be pursued after treatment. The evidence for many of these dietary changes is not as strong as that of your primary treatment and, therefore, not as necessary to incorporate. Dietary changes take time to evolve and a safe diet is much more important than making such changes. There are very important nutrients that may play a significant role in the maintenance of a strong immune system as well as general health.