What to know before eating forms of soy like tofu, tempeh, soy milk, and edamame.
Soy has gotten a bad rap over the years, but it can be a smart addition to your diet if you eat it the right way. Soy provides a variety of nutrients, including omega-3 fatty acids and fiber. Some forms of soy, like tofu and tempeh, are also healthy alternatives to animal proteins. (Animal sources of protein can have more heart-harming saturated fat than plant-based sources.) If eating more soy helps you displace some meat in your diet, great.
The debate over soy mainly has to do with phytoestrogens, which are plant-derived compounds (found in soybeans) that were believed to behave similarly to estrogen in the body. For years, there’s been a concern that soy may promote the growth of hormone-sensitive breast cancers. Science has gone back and forth on whether phytoestrogens are beneficial or carry health risks. But the latest research suggests that soy phytoestrogens don’t work exactly like estrogen. In fact, recent large analyses have concluded that a diet high in soy does not increase the chances of developing breast cancer and may even reduce the risk, though more research is needed to support the latter finding. (It’s also worth noting that there’s little research on breast health and soy supplements, which are more concentrated and stripped of other nutrients, so they’re not currently recommended.) Studies have also shown that a diet high in soy whole foods may help lower heart disease risk and reduce menopause-related hot flashes.
My verdict: It’s safe to eat one or two servings of soy a day, as long as it’s from a natural source or minimally processed. Good options include three ounces of tofu, a half cup of edamame, a cup of soy milk, or one-third cup of soy nuts.
Health’s medical editor, Roshini Rajapaksa, MD, is assistant professor of medicine at the NYU School of Medicine.