Genistein and daidzein are also antioxidants. When estrogen is high, isoflavones exert an anti-estrogenic effect because they occupy the doorway and block estrogen from entering cells. However, when estrogen is low, isoflavones provide additional weak estrogen activity. Soy-foods are on the cutting edge of research on these topics. Twenty-five grams per day resulted in half the cholesterol reduction in these groups.
Research continues to clarify soy's role.
It is also too early to make definitive statements about the effects of soy intake on hot flashes and night sweats, although many women report that soyfoods help. Soy's estrogenic effect may be the responsible factor. But his best guess is 20-30 grams of soy protein per day. Try mixing and matching soy foods until you find a combination you like. Isoflavones are only found in soyfoods - the less processed the better.