In recent years I have talked to breast cancer survivors about getting them on a healthier life style and diet. As we spoke about diet, soy has always come to the surface as a hazardous food that they were told to avoid by their doctor.
I would ask why the doctor told them this and the reply was always something like this “Soy foods contain estrogen that could feed cancer cells in their body and thus start their cancer again.”
The internet has not helped the issue either with anti-soy propaganda that is not scientific and lacks integrity.
Now, with that said I want to state that you should always follow your doctors treatment plan. I am not in anyway saying that you should ignore your doctor if they have told you not to consume soy products, but I am only presenting what I have found in my limited research about this subject.
I am seeing that this kind of prescription to stay away from soy foods is starting to go by the way side because there is a alot of scientific evidence now showing that whole soy foods are not only safe for cancer survivors but even healthful.
When eating soy it should always be eaten in its minimally processed forms like edamame, tempeh, tofu and unsweetened soy milk. Products containing unnaturally concentrated soy protein like protein powders and highly processed soy products lack the beneficial nutrients that are in the whole bean and in my opinion these products should be avoided. I also stay away from genetically modified soy (GMO). Choose “organic” soybean products, they are not genetically modified.
The research has overwhelmingly shown that the consumption of whole or minimally processed soy foods as discussed above is healthful and provides many nutritional benefits.
The research shows that these foods protect against breast cancer. A study done in 2009 meta-analysis on soy and prostate cancer found that a higher intake of soy was associated with a 26% reduction in risk.- (1)
Also it appears that isoflavones found in whole soy foods have anti-cancer effects that are not related to their ability to bind the estrogen receptor. Soy foods are not only associated with decreased risk of hormonal cancers, but also lung, stomach, and colorectal cancers. – (2-4)
Here is a quote from Dr. McCullough who is strategic director of nutritional epidemiology for the American Cancer Society on soy:
“More research is needed to understand the relationship between specific forms of soy and doses of isoflavones on cancer risk and recurrence. We also need to learn more about childhood exposure to isoflavones and risk of cancer. Until more is known, if you enjoy eating soy foods, the evidence indicates that this is safe, and may be beneficial (but note that miso, a fermented soy product, is high in sodium.) It is prudent to avoid high doses of isolated soy compounds found specifically in supplements, as less is known about their health effects. As for other “hidden” sources of soy proteins, the evidence to date does not suggest harm or benefit. However, if you are concerned about these products, you can choose to avoid them.” 4/8/14 Link to complete and original quote
Here is a quote from the American Cancer Society guidelines on nutrition and physical activity for cancer prevention:
“Can soy-based foods reduce cancer risk? As with other beans or legumes, soy and foods derived from soy are an excellent source of protein and a good alternative to meat. Soy contains several phytochemicals, including isoflavones, which have weak estrogen-like activity and may help protect against hormone-dependent cancers. There is growing evidence that eating traditional soy foods such as tofu may lower the risk of cancers of the breast, prostate, or endometrium (lining of the uterus), and there is some evidence it may lower the risk of other cancers. Whether this applies to foods that contain soy protein isolates or textured vegetable protein derived from soy is not known. There is little data to support the use of supplements of isolated soy phytochemicals for reducing cancer risk.” Link to the entire document in PDF
They have observed many times the connection between minimally processed soy intake and the reduced risk of cancers.
This is not to say or do I promote eating a lot of soy foods in the detriment of leaving out other foods from your diet. All whole foods work together for our health and there is no magical super-food that on its own will be the “One”, but on the contrary, you need them all to be wholly healthy. (Here is a bonus tip at no extra charge. An outstanding book to read on the subject of how whole foods work together for optimal nutrition is the book “Whole: Rethinking the Science of Nutrition” by T. Colin Campbell. PhD)
Not only are soy beans healthy but all beans eaten in variety, along with other fruits and vegetable are health promoting as they work together, not alone.
In conclusion, I am avoiding highly processed soy foods and I try to eat a variety of whole natural plant foods including all types of beans as well as some edamame, tofu and tempeh.
1. Hwang YW, Kim SY, Jee SH, et al: Soy food consumption and risk of prostate cancer: a meta-analysis of observational studies. Nutr Cancer 2009;61:598-606.
2. Yang WS, Va P, Wong MY, et al: Soy intake is associated with lower lung cancer risk: results from a meta-analysis of epidemiologic studies. Am J Clin Nutr 2011;94:1575-1583.
3. Kim J, Kang M, Lee JS, et al: Fermented and non-fermented soy food consumption and gastric cancer in Japanese and Korean populations: a meta-analysis of observational studies. Cancer Sci 2011;102:231-244.
4. Yan L, Spitznagel EL, Bosland MC: Soy consumption and colorectal cancer risk in humans: a meta-analysis. Cancer Epidemiol Biomarkers Prev 2010;19:148-158.
Photo Credit: Will Curran