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By Greg Arnold, DC, CSCS, April 14, 2007, abstracted from “Soy isoflavone intake inhibits bone resorption and stimulates bone formation in menopausal women: meta-analysis of randomized controlled trials” printed online in the European Journal of Clinical Nutrition
Between 1950 and 2000, the life expectancy for women increased by an average of 8 years.1 But this increased life expectancy also brings with it an increased risk of osteoporosis and bone fractures. While there are expected to be 650,000 osteoporosis-related fractures each year by 2050,2 osteoporosis is a “major public health threat” for 34 million Americans.3
Interest in soy isoflavones for bone health has stemmed from the fact that the incidence of osteoporosis-related fracture is significantly lower in Southern and Eastern Asian women than in Western women.(6, 7) In the study, researchers examined data from five randomized controlled trials that supplemented soy isoflavones in doses ranging from 37.3–118 mg per day and ranged from 4 to 48 weeks.
The researchers found that soy isoflavone intake significantly decreased the rates of bone breakdown compared to controls. Specifically, researchers cited research showing best results with at least 90 mg of isoflavones per day8 and for isoflavones to be taken for at least 12 weeks.9
For the researchers, “the results clearly suggested that isoflavones contribute significantly to inhibiting bone resorption and stimulating bone formation, especially in post-menopausal women.”
Reference:
1 “Life Expectancy” posted on http://mchb.hrsa.gov/whusa02/Page_26.htm
2 “Falls and Hip Fractures” posted on the American Acadmey of Orthopedic Surgeons Website http://orthoinfo.aaos.org/fact/thr_report.cfm?Thread_ID=77&topcategory=Hip
3 “Fast Facts on Osteoporosis” posted on the National Osteoporosis Foundation website
4 Zhang, X., X. O. Shu, et al. (2005). "Prospective cohort study of soy food consumption and risk of bone fracture among postmenopausal women." Arch Intern Med 165(16): 1890-5
5 Ma D-F. Soy isoflavone intake inhibits bone resorption and stimulates bone formation in menopausal women: meta-analysis of randomized controlled trials. Eur Jou Clin Nutr epub March 28, 2007; doi:10.1038/sj.ejcn.1602748
6 Ho SC, Bacon WE, Harris T, Looker A, Maggi S (1993). Hip fracture rates in Hong Kong and the United States, 1988 through 1989. Am J Public Health 83, 694–697
7 Tham DM, Gardner CD, Haskell WL (1998). Clinical review 97: potential health benefits of dietary phytoestrogens: a review of the clinical, epidemiological, and mechanistic evidence. J Clin Endocrinol Metab 83, 2223–2235
8 Dalais FS, Ebeling PR, Kotsopoulos D, Mcgrath BP, Teede HL (2003). The effects of soy protein containing isoflavones on lipids and indices of bone resorption in postmenopausal women. Clin Endocrinol 58, 704–709 9 Mori M, Aizawa T, Tokoro M, Miki T, Yamori Y (2004a). Soy isoflavone tablets reduce osteoporosis risk factors and obesity in middle-aged Japanese women. Clin Exp Pharmacol Physiol 31 (Suppl 2), S39–S41
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