Whether its edamame, tofu burgers, soy milk or just adding soy beans to your stew, soy is the new buzz food. Chances are though that if you are like me and you read a few too many blogs, you might be feeling a little confused regarding the safety of soy especially with regards to cancer. Let’s clear up the confusion and look at the scientific research.
SOYA IS GOOD FOR YOU
Soy contains many nutrients and boasts numerous health benefits. It is high in nutrients such as protein and fibre. The US Food and Drug Administration have approved a health claim to say that soy protein reduces the risk of heart disease. The fibre in soy also contributes to reducing the incidence of stomach and colorectal cancers. So we are well aware of the fact that soy is a good food, but why the cancer concern1?.
WHAT ABOUT CANCER?
The phytoestrogens in soy are thought to be the main concern around consuming soy and cancer. Many cancers such as breast cancer are hormone related and it is theorised that these phytoestrogens may work a lot like oestrogen, thus increasing your risk. One should note, however, that phytoestrogens don’t always mimic oestrogens. In some tissues they actually block the action of oestrogen. If soy’s oestrogen-blocking action occurs in the breast, then eating soya could, in theory, reduce the risk of breast cancer2.Remember that it’s important to note why there can be variations in research results. Some research is done on animal models and may not be a true reflection of how humans would react. It is therefore important to look at human studies for accurate information3.
When it comes to breast cancer prevention, the research gives no clear answer. Studies show a beneficial effect or no effect at all. But it’s important to note that in countries such as Asia where they consume large amounts of soy, there is less risk and incidence of breast cancer2,Most of the scary research that suggests that soy can increase breast cancer risk is done using high doses of concentrated soy protein supplements and not soy found in desirable forms. Perhaps then the problem is with more processed forms of soy 4, 5.
The timing of soy intake may also make a difference. The Shanghai Women’s Health Study found that women who consumed soy during adolescence and young adulthood had decreased risk of pre-menopausal breast cancer as compared to women who had low intakes of soy6. In the case of breast cancer survivors, one study of both U.S. and Chinese women found that soy food consumption was associated with a reduced risk of breast cancer recurrence2.
Consuming soy can help prevent prostate cancer. Research has proved conclusively that the isoflavones, specifically genistein, in soy help to reduce the incidence of prostate cancer. It can also slow the growth and metastasis of the cancer in already affected individuals. One such study suggest that tomato and soy when eaten together will help more than when each is eaten seperately7.
Animal studies show mixed effects of soy on cancer however human studies have not shown soy to be harmful to humans. Moderate consumption of soy is not only good for heart health but also for cancer prevention. Until more research is done, one should consider avoiding highly processed soy products. We may continue to enjoy foods containing soy, because not only is it one of the healthiest foods out, but it may decrease your risk for cancer.
- de Lemos, M.L., Effects of soy phytoestrogens genistein and daidzein on breast cancer growth. Ann Pharmacother, 2001. 35(9): p. 1118-21.
- Taku, K., et al., Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials. Menopause, 2012. 19(7): p. 776-90.
- Lee, S.A., et al., Adolescent and adult soy food intake and breast cancer risk: results from the Shanghai Women’s Health Study. Am J Clin Nutr, 2009. 89(6): p. 1920-6