As a former vegetarian, I’ve consumed more than my fair share of soy products. And I’m not alone: Vegans, health nuts, and the lactose intolerant alike have welcomed soy as an easy, cheap, and tasty way to get enough protein without the help of meat or dairy. But could this soy craze be bad for our health? Research suggests soy might mess with that essential hormone balance and derail physical development.
Soy Bad — Why It’s Dangerous
Soy isn’t just for the veg-heads among us — in fact, it’s everywhere, in many supermarket products (by some estimates up to 70 percent!). Whether such high levels are safe for consumers is hotly debated. The issue stems from soy’s phytoestrogens, compounds that mimic estrogen in the body. There’s conflicting research on the effects of phytoestrogens, but evidence is serious enough that the American Heart Association issued a warning against the use of soy supplements in food or pills. So what’re the major fears?
Women aren’t immune either: Soy consumption might mess with menstrual cycles, decrease fertility, and increase the risk for breast cancer (though cancer research is mixed — in fact, soy might help some women with breast cancer and might be a serious risk for others; it all comes down to the type of breast cancer a woman has)   . In younger girls, soy might induce premature puberty .
In both genders, soy can interfere with the endocrine system, which regulates mood, growth, and development, and the thyroid, which helps the body use energy and ensures proper functioning of the brain, heart, muscles, and other organs  . And despite big claims, soy isn’t the best muscle fuel; it’s less effective than whey or milk protein when it comes to muscle protein synthesis.
Soy, Much Better — Your Action Plan
Whether soy is awesome or dangerous might come down to how much and what kinds of soy a person consumes . Genetically modified soy consumption in particular has shown devastating results in animal-based studies, including severely reduced fertility, slower growth, higher mortality, and (brace yourself) testicles that changed from pink in color to dark blue (granted, these results were in mice) . But back in the human world, traditionally fermented soy products (think tofu or tempeh) seem to be healthy for humans in reasonable quantities.
Love that tofu? Good news is you probably don’t have to give up soy completely . Just follow these guidelines to minimize any potential harm.
- Avoid highly processed soy products. Read labels. Beware of protein bars and fake meat, and stick to whole soy foods, like edamame and tofu.
- Stick to fermented. Fermentation reduces the level of phytoestrogens in soy by as much as a third. Fermented products include soy sauce, miso, tempeh, and (for the more daring among us) natto.
- Avoid fast foods. As if we needed another reason: Fast food is a common source of hidden soy ingredients, meaning regular fast food consumption equals regular consumption of large quantities of soy.
- Get enough iodine. Eating the RDA of iodine (150mcg) should prevent any thyroid problems that might otherwise result from munching down on too much soy . Good sources include cod, shrimp, tuna, milk, baked potatoes, and seaweed.
- Diversify your diet. Whether you’re animal-free or as carnivorous as they come, choosing variety instead of the same old soy-laden products is good for your health.
Are you a die-hard soy devotee, or just a little skeptical? Tell us in the comments below, or tweet the author @LauraNewc.