AltmedWatch
the latest research on complementary and alternative medicine
ALTMED WATCH
The latest research on complementary and alternative medicine
Soy isoflavones and bone loss
Soy isoflavones may reduce spinal bone loss in perimenopausal women, according to a recent randomized, double-blind study. To reach that conclusion, investigators fed either isoflavone-rich soy (80 mg/day of isoflavone), isoflavone-poor soy (4.4 mg/day), or whey to about 70 women over 6 months. After doing multiple regression analyses to take into account confounding factors, the researchers found that a high isoflavone diet had a significant positive effect on the bone mineral density and bone mineral content of the lumbar spine.1
These results corroborate the findings of a similar trial that found 40 g of soy protein containing 90 mg/day of isoflavones, also given for 6 months, had a beneficial effect on the lumbar spinebut not on other bone sites.2
An editorial accompanying the newest trial cautions, however, that 6-month studies are really too short to assess the effects of soy on a clinical outcome like fracture rate because the bone remodeling cycle typically takes up to 80 weeks.3 Despite this precaution, the data are consistent with the hypothesis that soy isoflavones have an estrogenic effect on bone.
1. Alekel DL, St Germain A, Peterson CT, et al. Isoflavone-rich soy protein isolate attenuates bone loss in the lumbar spine of perimenopausal women. Am J Clin Nutr. 2000;72:844-852.
2. Potter SM, Baum JA, Teng H, et al. Soy protein and isoflavones: their effects on blood lipids and bone density in postmenopausal women. Am J Clin Nutr. 1998;68(Suppl):1375S-1379S.
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