TitleGenistein administered as a once-daily oral supplement had no beneficial effect on the tibia in rat models for postmenopausal bone loss.
Publication TypeJournal Article
Year of Publication2013
AuthorsTurner, RT, Iwaniec, UT, Andrade, JE, Branscum, AJ, Neese, SL, Olson, DA, Wagner, L, Wang, VC, Schantz, SL, Helferich, WG
JournalMenopause (New York, N.Y.)
Date Published06/2013

OBJECTIVE: Estrogen deficiency after menopause results in rapid bone loss, predisposing women to osteoporotic fractures. Genistein, a phytoestrogen present in high concentrations in soy, is an ingredient in dietary supplements aggressively marketed for bone health. However, in a recent long-duration clinical trial in postmenopausal women, the efficacy of soy extracts in reducing bone loss was disappointing. To better understand the failure of soy extracts to consistently induce a robust skeletal response in women, we investigated the long-term (5 mo) efficacy of genistein, administered as a daily oral supplement, (1) in preventing cancellous bone loss in skeletally mature virgin Long-Evans rats ovariectomized at 7 months of age and (2) in improving cancellous bone mass and architecture in aged retired-breeder rats ovariectomized at 16 or 22 months of age. METHODS: Rats within each age group were randomly assigned into one of three treatment groups (n = 7-12 rats/group): (1) vehicle control, (2) genistein 485 μg/day, or (3) genistein 970 μg/day, resulting in mean (SE) serum genistein levels of 0.18 (0.10), 0.76 (0.15), and 1.48 (0.31) μM, respectively. Total tibia bone mass and density were evaluated using dual-energy x-ray absorptiometry, whereas cancellous bone mass and architecture in the tibial metaphysis, as well as cortical bone mass and architecture in the tibial diaphysis, were evaluated by micro-CT. RESULTS: Oral genistein administered as a dietary supplement did not influence the cumulative effects of ovariectomy, aging, and/or reproductive history on cancellous and cortical bone mass and architecture. CONCLUSIONS: Serum levels of genistein similar to those in women consuming a high-soy diet are ineffective in preventing or treating bone loss in rat models for postmenopausal osteoporosis.