+/-Bones: Some studies suggest that because soy isoflavones can mimic estrogen (which helps maintain bone mass), eating soy helps protect against bone loss, particularly in postmenopausal women whose estrogen levels are declining. But recent research doesn’t show any protection.
A yearlong study showed that getting 110 milligrams of isoflavones (about 11⁄2 cups tofu or 1 cup shelled edamame) each day did not prevent bone loss in postmenopausal women. Researchers reviewing 17 studies in peri- and postmenopausal women reached the same conclusion. What’s more, soybeans (like all beans) contain phytic acid, a natural plant substance that interferes with the absorption of bone-building calcium, magnesium and iron.
+/-Breasts: While there have been concerns about soy and breast health, recent research has shown that women who ate as little as one daily serving of whole soyfoods—such as edamame or tofu—throughout childhood and adolescence lowered their breast-cancer risk later in life by as much as 50 percent. Too bad eating soy as an adult doesn’t offer the same protective benefits: “The evidence suggests that adult soy consumption does not decrease risk,” says Messina.Next: The Bottom Line About Soy »