You’ve just been diagnosed with cancer. What should you eat? A low-carb, Atkins-like diet? A Paleo diet? A vegetarian diet? The Mediterranean Diet? It doesn’t matter? A group of researchers sought to answer this question by applying the precautionary principle to evidence for which a dietary influence on cancer risk was substantial. Their work was published last month:
Applying the Precautionary Principle to Nutrition and Cancer, Journal of the American College of Nutrition, 28 May 2014
The precautionary principle is a scientifically and legally defined concept based on the view that there is a social responsibility to protect the public from harm when investigation has found a plausible risk. It places the burden of proof on those recommending the risk.
For example, the current body of evidence indicates that dairy food increases the risk for prostate cancer. Applying the precautionary principle would have us limit our consumption of dairy. Those recommending consumption of dairy must show that it does not contribute to cancer.
Based on these researchers’ investigation, this is what you should, or shouldn’t eat (“where evidence is sufficiently compelling”):
- Limit or avoid dairy products to reduce risk of prostate cancer.
- Limit or avoid alcohol to reduce risk of cancers of the mouth, pharynx, larynx, esophagus, colon, rectum, and breast.
- Avoid red and processed meat to reduce risk of cancers of the colon and rectum.
- Avoid grilled, fried, broiled, and other meats (meat here refers to red meat, poultry, and fish) cooked at high temperatures to reduce risk of cancers of the colon, rectum, breast, prostate, kidney, and pancreas.
- Eat soy products. If comsumed during adolescence they may reduce risk of breast cancer in adulthood. Soy products may also reduce risk of recurrence and mortality for women previously treated for breast cancer.
- Eat fruits and vegetables to reduce risk of several common forms of cancer.
I’ve picked out some mechanisms:
- Dairy – Contributes to prostate cancer risk via a large calcium dose that suppresses vitamin D activation, and by the tendency of milk to increase serum IGF-I concentrations.
- Alcohol – Contributes to cancer risk via harmful effects of metabolites of alcohol such as acetaldehyde, via lipid peroxidation, and generation of free-radical oxygen species. Alcohol may also disrupt folate metabolism.
- Red and Processed Meat – Contributes to cancer risk via abundance of heme iron, nitrites, heterocyclic amine formation, and the overabundance of essential amino acids and other nutrients that promote cell growth.
- Cooked Animal Foods – Contain heterocyclic amines (HCAs) that are genotoxic, mutagenic compounds formed from creatine and amino acids in cooked skeletal muscle, increasing in concentration with longer cooking times and higher temperatures. The National Toxicology Program lists 4 HCAs as “reasonably anticipated to be a human carcinogens.”
- Soy – Reduces cancer risk via ability of genistein [a phytoestrogen] to increase apoptosis [cancer cell death] and to reduce cell proliferation and blood vessel growth and to modulate sex hormone effects. Soy and other legumes are high in beneficial antioxidants.
- Fruits and Vegetables – Reduces cancer risk via antioxidants which limit reactive oxygen species. Some components may have antitumor properties, such as glycosylates (a precursor to isothiocyanates) and indole-3-carbonol (precursor to 3,3′-diindolylmethane), which have been shown to induce phase II enzymes responsible for eliminating reactive oxygen species and repairing DNA systems. Some components in soybeans, green tea, turmeric, grapes, tomatoes, and other plant foods have the ability to regulate apoptosis, an important pathway for cancer prevention.
“Overall, evidence suggests that diets emphasizing foods from plant sources—vegetables, fruits, whole grains, and legumes — are associated with lower cancer risk.”