A systematic review and meta-analysis of the effects of isoflavone formulations against estrogen-deficient bone resorption in peri- and postmenopausal women

Abstract

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. 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. We systematically searched EMBASE and PubMed for randomized controlled trials (RCTs) evaluating isoflavone therapies for treating BMD loss at the lumbar spine and femoral neck in estrogen-deficient women. Separate meta-analyses were carried out with the use of random-effects models for the lumbar spine and femoral neck for all studies providing isoflavones as aglycones. Twenty-six RCTs ( = 2652) were included in the meta-analysis. At the lumbar spine, isoflavone treatment was associated with a significantly ( < 0.00001) higher weighted mean difference (WMD) of BMD change of 0.01 (95% CI: 0.01, 0.02) than the control. For the femoral neck (18 RCTs, = 1604), isoflavone treatment showed a significantly ( < 0.01) higher WMD of BMD change of 0.01 (95% CI: 0.00, 0.02) compared with the control. When isolating studies that provide isoflavone aglycones in their treatment arm, the average effect was further significantly increased at the spine (5 RCTs, = 682) to 0.04 ( < 0.00001; 95% CI: 0.02, 0.05) and femoral neck (4 RCTs, = 524) to 0.03 ( < 0.05; 95% CI: 0.00, 0.06) compared with the control. This protective effect against bone loss disappeared when only studies with formulations comprising predominantly isoflavone glycosides were included. 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.

Effects of Dietary Phytoestrogens on Hormones throughout a Human Lifespan: A Review

“…Phytoestrogen effects on urinary estrogen metabolites have been studied in order to assess their potential protective role against breast cancer. One of the most recent studies reports an increase in the 2:16α-OH-E1 ratio after red clover-derived isoflavone supplementation in postmenopausal osteopenic women [103]. These results are consistent with prior research that found an increase in the 2:16α-OH-E1 ratio after flaxseed supplementation [104,105].…”

“…et al demonstrated that red clover-derived isoflavones combined with probiotics attenuated estrogen-deficient bone mineral density loss and improved bone turnover even in postmenopausal women with osteopenia [ 177 ]. Moreover, a recent meta-analysis and systematic review of RCT with perimenopausal and postmenopausal women concluded that isoflavones can be effective in preserving bone mineral density and attenuating accelerated bone resorption [ 103 ]. A possible explanation for these contrasting results could be that estrogens are predominantly antiresorptive agents, so the beneficial effects of phytoestrogens may arise from decreased bone resorption by osteoclasts rather than increased bone formation by osteoblasts.…”

Isoflavone Supplements for Menopausal Women: A Systematic Review

“…The spine in particular is thought to be the most sensitive to isoflavones because it has a higher content of trabecular bone compared to cortical bone. Trabecular bone has a higher expression of ERβ and a larger surface area for receptor binding [35]. The hip, on the other hand, contains a higher percentage of cortical bone, and is remodeled slower than the spine [36].…”

Aqueous extract from Opuntia megapotamica fruit pulp promotes osteoblast activity

“…The World Health Organization (WHO) proposes to increase research aimed at examining the potential benefi ts of medicinal plants use in different pharmacological approaches for diseases treatments [12]. There is a growing interest in the study of natural products derived from plants for treatment of bone conditions [13][14][15][16][17]. This is, in part, because they offer the possibility of longer exposure times and fewer secondary complications compared to synthetic drugs [18,19].…”