D. Lee Alekel, A. St. Germain, C.T. Peterson, K.B. Hanson, J.W. Stewart, T. Yoda. Published in The American Journal of Clinical Nutrition, 2000 72:844-852.
Many older women experience bone loss that may lead to osteoporosis due to reduced estrogen levels following menopause. Estrogen and other hormone-replacement therapies can be used to help prevent bone loss, but may have undesirable side effects, such as increased breast and endometrial cancer risk.
Soy contains isoflavones, which are structurally similar to estrogen and may be a potential alternative to hormone-replacement therapy. This 24-week, double-blind clinical trial examined the effects of soy protein consumption on bone loss in women during menopausal transition. Sixty-nine perimenopausal women, randomly assigned to one of three treatment groups, received daily soy protein with isoflavones (80.4mg aglycone components), soy protein without isoflavones (4.4mg aglycone components), or whey protein (control).
Bone loss was determined by measuring bone mineral density and bone mineral content of the lumbar spine, while bone resorption was determined by measuring levels of two biochemical markers.
The results indicate that soy with isoflavones attenuate spinal bone loss, while the soy without isoflavones and the control did not affect spinal bone loss. None of the treatments affected bone resorption. These findings suggest that soy isoflavones may help decrease the rate of bone loss during menopause and may serve as an alternative adjuvant therapy in the prevention of osteoporosis.
Funding for this study provided by Hatch Act and State of Iowa funds, US Department of Agriculture, and Iowa State University.