Conclusions : Isoflavone treatments exert a moderately beneficial effect against  estrogen-deficient bone loss in women .
The effect appears dependent on whether isoflavone treatments are in aglycone form ; we conclude that beneficial effects against bone loss may be enhanced for isoflavone aglycones
Background : Age-related estrogen deficiency leads to accelerated bone resorption .
There is evidence that , through selective estrogen receptor modulation , isoflavones may exert beneficial effects against  estrogen-deficient bone loss .
Isoflavone aglycones show higher bioavailability than their glycosidic counterparts and thus may have greater potency .
Objective : To summarize evidence , we executed a systematic review and meta- analysis examining isoflavone therapies and bone mineral density ( BMD ) loss in peri- and postmenopausal women .
The soy isoflavones for reducing bone loss (SIRBL) study: a 3-y randomized controlled trial in postmenopausal women.
BACKGROUND Our previous study indicated that soy protein with isoflavones lessened lumbar spine bone loss  in midlife women . OBJECTIVE We examined the efficacy of isoflavones ( extracted from soy protein ) on bone mineral density ( BMD ) in nonosteoporotic postmenopausal women . We hypothesized that isoflavone tablets would spare BMD , with biological ( age , body weight , serum 25-hydroxyvitamin D ) and lifestyle ( physical activity , dietary intake ) factors modulating BMD loss . DESIGN Our double-blind , r and omized controlled trial ( 36 mo ) included healthy postmenopausal women ( aged 45.8 - 65.0 y ) with intent-to-treat ( n = 224 ) and compliant ( n = 208 ) analyses . Treatment groups consisted of a placebo control group and 2 soy isoflavone groups ( 80 compared with 120 mg/d ) ; women received 500 mg calcium and 600 IU vitamin D(3 ) . Outcomes included lumbar spine , total proximal femur , femoral neck , and whole-body BMD . RESULTS Analysis of variance for intent-to-treat and compliant ( > or = 80 % ) models , respectively , showed no treatment effect for spine ( P = 0.46 , P = 0.21 ) , femur ( P = 0.86 , P = 0.46 ) , neck ( P = 0.17 , P = 0.14 ) , or whole-body ( P = 0.86 , P = 0.78 ) BMD . From baseline to 36 mo , BMD declined regardless of treatment . In intent-to-treat and compliant models , respectively , BMD decreases were as follows : spine ( -2.08 % , -1.99 % ) , femur ( -1.43 % , -1.38 % ) , neck ( -2.56 % , -2.51 % ) , and whole body ( -1.66 % , -1.62 % ) . Regression analysis ( compliant model ) indicated that age , whole-body fat mass , and bone resorption were common predictors of BMD change . After adjustment for these factors , 120 mg ( compared with placebo ) was protective ( P = 0.024 ) for neck BMD . We observed no treatment effect on adverse events , endometrial thickness , or bone markers . CONCLUSION Our results do not show a bone-sparing effect of extracted soy isoflavones , except for a modest effect at the femoral neck . This trial was registered at clinical trials.gov as NCT00043745
Conclusions : Isoflavone treatments exert a moderately beneficial effect against  estrogen-deficient bone loss in women .
The effect appears dependent on whether isoflavone treatments are in aglycone form ; we conclude that beneficial effects against bone loss may be enhanced for isoflavone aglycones
Background : Age-related estrogen deficiency leads to accelerated bone resorption .
There is evidence that , through selective estrogen receptor modulation , isoflavones may exert beneficial effects against  estrogen-deficient bone loss .
Isoflavone aglycones show higher bioavailability than their glycosidic counterparts and thus may have greater potency .
Objective : To summarize evidence , we executed a systematic review and meta- analysis examining isoflavone therapies and bone mineral density ( BMD ) loss in peri- and postmenopausal women .