Soy may be the most controversial food of our modern time. It seems that everyone, nutrition professional or not, has an opinion on whether soy is healthy; proven by a quick google search that produces thousands of articles on the dangers of soy. Last week, as I was checking out at the grocery store, the attendant looked at my bag full of tofu, tempeh and veggie burgers and interjected that ‘I was better off eating meat than ingesting all of that soy.’ As I defended my purchases and tried to set the record straight, I couldn’t help but wonder, how did soy, one of nature’s most perfect foods, become so misunderstood?
Most of the confusion seems to stem from soy’s phytoestrogen content. It’s true that estrogen has been linked to an increased risk of breast cancer, but phytoestrogens are not estrogens and don’t work the same way. Phytoestrogens are naturally-occurring plant compounds that are found in a number of foods, like soy. A series of health benefits can be attributed to consuming phytoestrogens: lowered risk of heart disease, osteoporosis, and yes- even breast cancer. We see this most notably in traditional Asian diets, which have high soy intake but low rates of cardiovascular disease, diabetes and breast cancer.
Digging a little deeper, we find that isoflavones, a class of phytoestrogens, can block other estrogens from binding to estrogen receptors, therefore reducing excess estrogen where it isn’t needed. This mechanism helps to explain why women who consume the most soy isoflavones have a lower risk of breast and other hormone dependent cancers. While studies do show mixed results on the potency and amount of soy needed for breast cancer reduction, it doesn’t seem to be harmful. Some studies suggest the effect of soy on breast cancer risk is most beneficial when consumed at an early age, when breast tissue is still developing.
To me, soy is a near-perfect food….