Effects of soy
isoflavones on
osteoporosis remain unclear. This review aimed to clarify the effect of soy
isoflavones on bone mineral density (BMD) and turnover markers in menopausal women. PubMed and the Cochrane Library were searched in July 2011 for relevant meta-analyses of randomized controlled trials evaluating effects of soy
isoflavones on BMD and bone turnover markers. Three meta-analyses evaluated the effects of soy
isoflavones on lumbar spine, total hip, femoral neck, and trochanter BMD. Soy
isoflavones significantly improved lumbar spine BMD in a moderate manner, but did not affect total hip, femoral neck, and trochanter BMD in menopausal women. Ingestion of soy
isoflavones for six months appeared to be enough to exert a beneficial effect on lumbar spine BMD. Two meta-analyses evaluated the effects of soy
isoflavones on a
bone resorption marker (urine
deoxypyridinoline) and two formation
markers (serum alkaline phosphatase and
osteocalcin). Soy
isoflavones significantly decreased urine
deoxypyridinoline in a moderate manner, but did not affect serum
alkaline phosphatase and
osteocalcin in menopausal women. Soy
isoflavones may prevent
postmenopausal osteoporosis and improve bone strength thus decreasing risk of fracture in menopausal women by increasing lumbar spine BMD and decreasing
bone resorption marker urine
deoxypyridinoline. Further studies are needed to address factors affecting the magnitude of the beneficial effects of soy
isoflavones and to assess the possible interactions between soy
isoflavones and anti-
osteoporosis drugs, and to verify effects on BMD of other skeletal sites and other bone turnover markers.