Soy protein isolate diet does not prevent increased cortical bone turnover in ovariectomized macaques.

Forty-one ovariectomized, cynomolgus monkeys were divided into 4 groups and fed a casein and lactalbumin based diet with or without 17beta-estradiol, or a soy protein based diet with or without 17beta-estradiol for 7 months. Histomorphometry was done on cortical bone from the mid-shaft femur. 17beta-estradiol suppressed ovariectomy-induced increases in bone formation rates, regardless of dietary protein source. Soy protein alone did not prevent increased bone turnover and on the endosteal surface, it actually increased bone turnover when compared to casein/lactalbumin fed monkeys.