It is believed that soy isoflavones can inhibit bone resorption and stimulate bone formation. Both in vivo and in vitro studies suggest that soy isoflavones may help maintain bone mineral density.
The study included 24,000 postmenopausal women without a history of fractures or hormone therapy. Their dietary habits were assessed through questionnaires, and the incidence of fractures was followed for four and a half years. The results showed that 1,770 fractures occurred among these patients. The fracture incidence was significantly lower in those who consumed more soy protein, and this finding remained unchanged even after adjusting for calorie intake, economic status, other nutrients, and risk factors for osteoporosis.
The effect was most pronounced in women within 10 years of menopause. Consuming soy may partially help reduce menopause-related bone loss, but for women who already have bone loss, the reversing effect is less significant.