Soy saves bones
Posted by Richard on February 29, 2008
Two new meta-analyses of soy studies provide strong confirmation that women can improve bone mineral density, inhibit bone resorption, and increase bone formation by supplementing with soy isoflavones. The meta-analyses, one by Chinese and one by Japanese researchers, appear in the February issue of the European Journal of Clinical Nutrition and the journal Clinical Nutrition, respectively. According to Life Extension Foundation (emphasis added):
The first meta-analysis found an average decrease in urinary deoxypyridinoline [bone resorption marker] of 2.08 nanomoles per millimole, and an average increase of 1.48 micrograms per liter of BAP [bone formation marker] in women who received isoflavones compared with those who received a placebo. “Isoflavone intervention significantly inhibits bone resorption and stimulates bone formation,” the authors stated. “These favorable effects occur even if less than 90 milligrams per day of isoflavones are consumed or the intervention lasts less than 12 weeks.”
The second review also found a bone-building benefit for soy. In the clinical trials examined, women who received soy experienced a significant increase of 20.6 milligrams per cubic centimeter in spine bone mineral density compared with those who received a placebo. Bone mineral content also increased, but to a lesser extent. Benefits were greater when more than 90 milligrams per day isoflavones were consumed, or when the trial lasted at least six months. “The results clearly suggested that isoflavones contributed significantly to the increase of spinal bone mineral density, especially in postmenopausal women,” Dr Wang and his coauthors conclude.
… The lower incidence of osteoporosis-related fracture among Asian women who consume 10 to 20 times more soy than Western women may point to a bone-protective effect of soy isoflavones. The authors recommend large randomized clinical trials using graded dosages of isoflavones to measure their long term effects on bone mass as well as fracture risk.
Larger studies would indeed be helpful. But if you're concerned about osteoporosis, you may not want to wait for those. You may want to take soy supplements or add soy milk, edamame, tempeh, or tofu to your diet. The latter, I understand, can be made quite palatable by wrapping it in bacon.
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