In the last decade, soy has received tremendous attention as an alternative to hormone replacement therapy because of its rich supply of isoflavones — compounds that can positively affect both menopausal symptoms and bone loss.
A research review by scientists at the Department of Nutrition, Loma Linda University in California indicated that soy foods and soybean isoflavone supplements help alleviate menopausal symptoms, particularly hot flashes. Thirteen trials involving more than 1,700 women were identified for the review. Based on analysis, there was a statistically significant relationship between the frequency of hot flashes and treatment with isoflavones.
Another study at the Department of Community and Family Medicine at the Chinese University of Hong Kong found that soy isoflavones have a favorable effect on bone loss in postmenopausal women with lower bone mass. In this double-blind, randomized controlled trial, 203 Asian women, aged 48 to 62 years with low initial bone mass, were assigned to one of three treatment groups: a mid-dose of approximately 40 mg of isoflavones, a high dose of approximately 80 mg of isoflavones, or a placebo. All three groups were given calcium and vitamin D daily. Bone mineral density and bone mineral content of the whole body, spine and hip were measured.
After one year, the researchers found that women in the high dose group had statistically significant improvements in bone mineral content in the hip compared to placebo and low dose groups.
Sources: J Med Food. 2003 Spring;6(1):1-11; J Clin Endocrinol Metab. 2003 Oct;88(10):4740-7