Impact of synbiotic supplementation on cardiometabolic and anthropometric indices in patients with metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials

Probiotic and synbiotic products are being widely used by a large number of patients and clinicians; however, effects on cardiometabolic indices in patients with the metabolic syndrome remain unclear. This meta-analysis aimed to evaluate the effects of a synbiotic intervention on lipid profile, insulin resistance, blood pressure, anthropometric parameters, and inflammatory markers. We searched MEDLINE, Scopus, and Clarivate Analytics Web of Science by October 2021. Studies were selected if they reported the effectiveness of the synbiotic intervention on cardiometabolic and anthropometric indices. The weighted mean difference was calculated as the effect size using a random-effects model. Subgroup analyses were conducted to determine sources of heterogeneity. Dose-dependent effects were assessed using a dose-response meta-analysis of differences in means. Five trials (1049 participants) were finally included in the meta-analysis. Synbiotic intervention significantly reduced serum insulin levels (WMD, −6.39 μU/mL; 95%CI, (−7.2 to −5.4); p = 0.001, I2 = 88.2%, N = 5), triglycerides (WMD, −20.3 mg/dl; 95%CI, (−32.7 to −7.8); p = 0.001, I2 = 87.7, N = 5), total cholesterol (WMD, −7.8 mg/dl; 95%CI, ( −12.5 to −3.02); p = 0.001; I2 = 66.7%, N = 5), low-density lipoprotein cholesterol (WMD, −9.02 mg/dl; 95%CI, (−10.8 to −7.2); p