The Effect of Isoflavones on Blood Pressure in Overweight Postmenopausal Women

The relationship between soy protein supplementation and blood pressure (BP) in postmenopausal women remains controversial. This systematic review and meta-analysis aimed to evaluate the effects of soy protein supplementation on BP in this population. A comprehensive search of PubMed, Science Direct, and the Cochrane Library was conducted through 2018. Randomized controlled trials (RCTs) were included, and weighted mean differences (WMDs) in BP changes were analyzed using fixed-effect or random-effect models. Meta-regression was performed to explore potential sources of heterogeneity. A total of 13 RCTs involving 1,031 postmenopausal women were included. The results indicated that soy isoflavone supplementation significantly reduced systolic blood pressure (SBP) compared to the control group (SMD=−0.151; 95% CI: −0.275 to −0.027; p=0.017). However, no significant effect was observed on diastolic blood pressure (DBP) (SMD=−0.025; 95% CI: −0.148 to 0.099; p=0.694). These findings suggest that soy isoflavone supplementation may provide a modest benefit in lowering SBP among postmenopausal women, while its effect on DBP remains unclear. Further high-quality studies are warranted to confirm these results, identify sources of heterogeneity, and determine the optimal dosage and duration of supplementation.