Genistein is an isoflavone phytoestrogen found primarily in legumes. It exhibits mild estrogenic activity compared to the endogenous hormone estradiol and preferentially activates estrogen-receptor beta (ER-beta). Due to its mild estrogenic properties, genistein has been studied for its role in supporting menopausal comfort and bone health in women. 

Mild Hot Flashes 

Genistein may promote estrogen homeostasis and help diminish mild hot flashes. Hot flashes are a common complaint of menopausal women and are understood to occur due to the postmenopausal decline of estrogen. A 12‐month, prospective, randomized, double‐blind, placebo‐controlled study with 247 postmenopausal women observed a 56.4% reduction in the mean number of hot flashes and a ~40% reduction in the severity of hot flashes in women who received genistein compared to a placebo. Another randomized controlled study (RCT) (n = 84) observed that women who were administered genistein for 12 weeks experienced a statistically significant 51% reduction in the number of hot flashes compared to a 30% reduction in the placebo group. The genistein group also exhibited fewer hot flashes per day and a decrease in the total duration of hot flashes per day at week 12 compared to the placebo.

Bone Health

Maintaining proper bone health is a major concern for postmenopausal women. Epidemiological evidence suggests that a high intake of isoflavones supports healthy bone metabolism. The beneficial effects of genistein on bone turnover (decreased bone resorption and enhanced formation) are attributed to its mild estrogenic activity on ER‐beta. A meta-analysis of RCTs (n = 1,240) evaluated the effect of isoflavone extracts on bone mineral density (BMD) in menopausal women. The researchers observed that after 6 to 12 months of isoflavone supplementation, women experienced a significant increase in spine BMD (but no significant effect was observed on the femoral neck, hip, or trochanter). Genistein has also been shown to promote calcium homeostasis to support normal BMD status. 

Metabolic Health 

Estrogen and ERs have an important role in promoting normal insulin signaling pathways and lipid metabolism. Partially owing to this, the association of chronic metabolic conditions, such as type 2 diabetes mellitus (T2DM) and cardiovascular disease, increases in women after menopause. Genistein may promote metabolic health through its demonstrated mild estrogenic, antioxidant, and anti-inflammatory properties. 

Postmenopausal women with T2DM (n = 54) who received genistein supplementation experienced significantly reduced fasting blood glucose, glycated hemoglobin, serum triglycerides, and malondialdehyde (MDA), and increased antioxidant status compared to the placebo group. Anthropometric changes were not significant. A meta-analysis (n = 476) of postmenopausal women with metabolic syndrome demonstrated that women administered genistein supplementation displayed significantly reduced homocysteine, LDL-cholesterol, total cholesterol, and triglycerides and significantly increased HDL-cholesterol. Further meta-analyses by Yi and colleagues and Liu and colleagues yielded similar results. One small RCT (n = 20) suggests that genistein may promote endothelial health in postmenopausal women by supporting normal flow-mediated dilation. 

Summary 

Genistein, an isoflavone phytoestrogen, may have multiple clinical benefits for supporting menopausal women. Due to its mild estrogenic activity, genistein may promote bone and metabolic health and may help diminish mild hot flashes.

By Danielle Moyer, MS, CNS, LDN