Does Soy Cause Man Boobs?

Answers to all your fitness questions.

Unless you eat tofu with a shovel, soy poses no credible threat to your manhood. Rumors that isoflavones, the "active ingredient" in soy, have the potential to cause feminization in men—à la erectile dysfunction, lower sperm counts, and man mammaries—have been floating around for years but with essentially no hard evidence. Studies suggesting the link have been inconclusive at best. A recent large, peer-audited review of available studies, published in May in the journal Fertility and Sterility, concluded that soy does not cause feminization (though its author did have ties to the soy industry). With soy, we're sure of one thing: It's an excellent source of low-fat, lactose-free protein for athletes, and its isoflavones help protect against problems like cancer, hypertension, and heart disease (to name a few). Since there are no studies of guys who, say, drink a tanker of soy milk, just consume it in moderation—say, two to four servings of tofu per day—and you won't need to worry about a jog bra.

Soy foods

Soy foods

A new class of sports drinks is emerging as a go-to source of fuel before you even begin to sweat. EAS's Peak ($3.50; and Gatorade's Prime 01 ($1.30; top off your energy stores with a slow-digesting sugar, called isomaltulose, that will still be giving you a trickle charge after two to three hours—much longer than the sugars in traditional sports drinks.

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Filed To: Nutrition
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