I’m willing to bet that, as athletes and fitness enthusiasts, most of us take active roles in determining what enters our bodies. Whether choosing food or dietary supplements, we prefer to do our own homework rather than rely on the infinite wisdom of chain stores and big-budget commercials to tell us what’s healthy. One of the latest pet projects of these mega-stores and product companies is soy, but what exactly is soy, and why is it so healthy (or not)? Below, I’ve broken down some of the benefits and potential risks of the bean in order to help you decide if eating more soy is right for you.
The Good
Soy has been a staple in Asian diets for thousands of years because, not only does it grow nicely in Asian climates, but its beans are also packed with complete proteins (a rarity for plant-based protein sources), soluble fiber, Vitamins K and B6, and calcium, magnesium, boron, phosphorus, potassium, zinc, and iron (making them great for non-red meat eaters). Oh, and they’re completely sodium-free.
The results of several research studies have suggested that eating soy can lower levels of LDL (“bad”) cholesterol and decrease several side effects of menopause, such as hot flashes, while other studies suggest the phytochemicals in soy can decrease the risk of cancer. Additionally, daidzein, one particular isoflavone in soy, is chemically and structurally similar to ipriflavone, a medication used to treat osteoporosis. Although most of these studies were conducted using soy supplements, observational studies of cultures—particularly those in eastern Asia—whose members tend to eat large amounts of soy in their everyday diets have shown results similar to the soy supplement-based research studies conducted by Western researchers; they have fewer cholesterol-related health complications, lower cancer rates, virtually no hot flashes, and minimal loss of bone density with age.
The Bad
As with anything touted as a “wonder drug,” “super food,” or other miracle cure-all, the backlash on soy has been strong and sometimes quite vocal. While I doubt eating soy will kill you, as some among the opposition claim, eating more soy might not be for everyone.
For example, some studies have shown the isoflavones in soy to mirror the effects of other naturally-occurring hormones in our bodies, and this hormonal response might not always be beneficial. In both animal- and human-based studies, one such isoflavone, genistein, has been shown to masculinize male and female fetuses when eaten by the mother during gestation and breastfeeding. The long-term side effects of this masculinization remain unknown. Also, eating large amounts of soy is not recommended for women who have had breast cancer or who have several risk factors for the disease, as the estrogenic effects of isoflavones can increase these risks.
The Verdict
We’ve all heard that “too much of a good thing is not a good thing” or something along those lines, and the saying definitely seems to apply to soy. The soybean is jam-packed with good stuff everyone can benefit from, and its protein and iron content make it an absolute staple to any vegetarian’s diet. However, soy does contain estrogen-like compounds called isoflavones. While most studies show that simply increasing the consumption of whole soy in a person’s regular diet will have negligible effects on hormone activity, taking large doses of concentrated soy supplements could potentially be harmful. The bottom line: the vast majority of us can benefit from eating more soy, but there’s just no reason to pound down soy pills.
Jessica Gereau has a BS in Kinesiology from San Francisco St. University. Before becoming a certified personal trainer she achieved a personal weight loss of 60+ lbs, and this has motivated her to help others obtain similar goals. She founded Gym Class Fitness Studio in the Bay Area as a place where people can learn what she learned along the way - that cookies are a part of life, and the hard way is the only way. Jessica currently carries certifications for ACSM and NASM.