It has been suggested that the oestrogenic effects of soy isoflavone may help prevent osteoporosis (Setchell & Cassidy 1999). A recent review of in vitro and in vivo studies suggests that soy protein prevents bone loss and that soy isoflavones stimulate the synthesis and the expression of alkaline phosphatases in osteoblasts, and food enriched with isoflavones prevented the reduction of bone mineral density (BMD) in ovariectomised rats or mice and inhibited excretion of urinary deoxypyridinoline (Horiuchi 2005). Animal studies have also found a synergy between soy isoflavones © 2007 Elsevier Australia
and supplemental calcium In Improving BMD, particularly in the lumbar spine (Ward 2005).
In human trials, 35 g/day soy protein for 12 weeks was found to significantly reduce urinary deoxypyridinoline and increase total alkaline phosphatase in a small study of 1 5 women aged 45-64 years (Roudsari et al 2005); however, randomised trials in humans suggest that soy protein and soy isoflavones do not significantly affect calcium metabolism in postmenopausal women (Spence et al 2005) or improve BMD (Horiuchi 2005), despite having an effect on markers of bone formation (Arjmandi etal 2005).
It has been suggested that the beneficial effects of soy isoflavones on bone may be life-stage specific and dependent on the number of oestrogen receptors and the endogenous hormone milieu. Perimenopausal and early menopausal women may therefore be more receptive to the therapeutic effects of isoflavones on bone loss prior to the diminution of oestrogen receptors that occurs in the postmenopausal years (Reinwald & Weaver 2006).
Was this article helpful?
Are Menopause Symptoms Playing Havoc With Your Health and Relationships? Are you tired of the mood swings, dryness, hair loss and wrinkles that come with the change of life? Do you want to do something about it but are wary of taking the estrogen or antidepressants usually prescribed for menopause symptoms?