effects of phytoestrogen isoflavones on bone density in women: a double-blind, randomized, placebo-controlled trial

• Published in: The American journal of clinical nutrition Vol. 79; no. 2; pp. 326 - 333
• Main Authors: Atkinson, C, Compston, J.E, Day, N.E, Dowsett, M, Bingham, S.A
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01-02-2004; American Society for Clinical Nutrition, Inc
• Subjects: Aged; Alternative medicine; Analysis; Biological and medical sciences; Body Mass Index; Bone and Bones - drug effects; Bone and Bones - metabolism; Bone Density - drug effects; Double-Blind Method; Estradiol - blood; Female; General pharmacology; Hormone replacement therapy; Humans; Isoflavones - pharmacology; Medical sciences; Middle Aged; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Phytoestrogens; Plant Preparations - pharmacology; Skeletal system; Human; Replacement therapy; Pharmacognosy; bone density; Supplemented diet; phytoestrogens; Flavonoid; Isoflavone derivatives; Feeding; randomized controlled trial; Osteoarticular system; Phytoestrogen; body composition; Health food; Randomized design; estrogen and vitamin D receptor polymorphisms; Placebo; Double blind study; Female; Bone mineral density; Bone; Isoflavones
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/79.2.326

Background: Isoflavone phytoestrogen therapy has been proposed as a natural alternative to hormone replacement therapy (HRT). HRT has a beneficial effect on bone, but few trials in humans have investigated the effects of isoflavones on bone. Objective: The objective of the study was to determine the effect on bone density of a red clover-derived isoflavone supplement that provided a daily dose of 26 mg biochanin A, 16 mg formononetin, 1 mg genistein, and 0.5 mg daidzein for 1 y. Effects on biochemical markers of bone turnover and body composition were also studied. Design: Women aged 49-65 y (n = 205) were enrolled in a double-blind, randomized, placebo-controlled trial; 177 completed the trial. Bone density, body composition, bone turnover markers, and diet were measured at baseline and after 12 mo. Results: Loss of lumbar spine bone mineral content and bone mineral density was significantly (P = 0.04 and P = 0.03, respectively) lower in the women taking the isoflavone supplement than in those taking the placebo. There were no significant treatment effects on hip bone mineral content or bone mineral density, markers of bone resorption, or body composition, but bone formation markers were significantly increased (P = 0.04 and P = 0.01 for bone-specific alkaline phosphatase and N-propeptide of collagen type I, respectively) in the intervention group compared with placebo in postmenopausal women. Interactions between treatment group and menopausal status with respect to changes in other outcomes were not significant. Conclusion: These data suggest that, through attenuation of bone loss, isoflavones have a potentially protective effect on the lumbar spine in women.