Menopausal women who increase their soy isoflavone consumption from dietary or supplemental sources for 6 months can boost bone-mineral density in the spine by almost 1 g, according to a meta-analysis of 10 randomized, controlled trials published in the February 2008 issue of the journal Clinical Nutrition. A total of 608 subjects provided data for the analysis, which reported the favorable effects were significant with consumption of approximately 90 mg of isoflavones per day.
Previous studies have reported conflicting results concerning bone health for postmenopausal women and soy isoflavones in doses varying from 40 to 99 mg/day. While the intake of isoflavones varied greatly among the trials used for this meta-analysis (ranging from 4.4 to 150 mg/day) and trial duration also varied (ranging from 3 to 24 months) the new meta-analysis results add to the debate by reporting that doses of 90 mg/day—or even slightly less—of soy isoflavones may improve bone density.
The study’s researchers report that isoflavone consumption was associated with an increase of 20.6 mg per sq cm in spine bone-mineral density (SBMD) compared to subjects consuming placebo. Moreover, isoflavone intake of more than 90 mg/day and lasting at least 6 months was responsible for a 28.5 and 27 mg per sq cm increase in SBMD, respectively. In addition, the spine bone mineral content was 0.93 g higher on average in subjects taking isoflavones compared to placebo.
Limiting bone loss in post-menopausal women could ease the burden of osteoporosis, a disease that affects half of all women over the age of 50 worldwide.
Source: online version of Integrative Medicine: A Clinician Journal, www.imjournal.com