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

Background: 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 metaanalysis aimed to evaluate the effects of a synbiotic intervention on lipid profile, insulin resistance, blood pressure, anthropometric parameters, and inflammatory markers. Methods: 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. Results: Five trials (1049 participants) were finally included in the meta-analysis. Synbiotic intervention significantly reduced serum insulin levels (WMD, -6.39 mu U/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 < 0.001, I2 = 0%, N = 5), waist circumference (WMD, -4.04 cm; 95%CI, ( - 4.9 to -3.08), p < 0.001; I2 = 22.7%, N = 3), body weight (WMD, -4.3 kg; 95%CI, (-6.2 to -2.5); p = 0.001; I2 = 0%, N = 2), systolic blood pressure (WMD, -1.8 mmHg; 95% CI, (-2.8 to -0.7); p = 0.001; I2 = 0%, N = 3), and serum interleukin-6 concentrations (WMD, -0.2 pg/mL; 95%CI, (-0.3 to -0.08); p = 0.001, I2 = 39.8%, N = 2), and increased high-density lipoprotein cholesterol levels (WMD, 2.3 mg/ dl; 95%CI, (0.2-4.4); p = 0.03; 03; I2 = 93.1%, N = 5). Synbiotic administration did not significantly affect fasting plasma glucose, homeostatic model assessment for insulin resistance, body mass index, diastolic blood pressure, heart rate, and serum C-reactive protein concentrations. Conclusions: The present findings suggest that synbiotic intervention effectively improves cardiometabolic risk factors in patients with metabolic syndrome.

Automated summary

Synbiotic intervention effectively improves cardiometabolic risk factors in patients with metabolic syndrome, including reducing serum insulin levels, triglycerides, total cholesterol, low-density lipoprotein cholesterol, waist circumference, body weight, systolic blood pressure, and serum interleukin-6 concentrations, and increasing high-density lipoprotein cholesterol levels.