Effects of Sumac Consumption on Blood Pressure, Glycemic Indices, and Body Composition in Adults: A GRADE-assessed Systematic Review and Dose-response Meta-analysis

Background: Owing to the rich phytochemical content of Rhus coriaria L. (Anacardiaceae), known as Sumac, it may affect blood pressure, glycemic, and anthropometric indices. We, therefore, aimed to examine evidence on effect of Sumac on these factors by conducting a meta-analysis of RCTs. Methods: A systematic literature search up to January 2024 was completed in PubMed/Medline, Scopus, and Web of Science. Heterogeneity tests of the selected trials were performed using the I2 2 statistic. Random effects models were assessed based on the heterogeneity tests, and pooled data were determined as weighted mean differences (WMD) with a 95 % confidence interval (CI). Results: Fifteen RCTs were included in this meta-analysis. Our findings showed that Sumac consumption significantly reduced diastolic blood pressure (DBP) (WMD =-2.88 mmHg; 95 %CI,-4.22 to-1.54; P = 0.001), fasting blood glucose (FBG) (WMD =-5.15 mg/dL; 95 %CI,-8.73 to-1.57; P = 0.005), insulin (WMD =-1.95 uIU/ml; 95 %CI, 3.11 to-0.79; P = 0.001), Hemoglobin A1c (WMD =-0.48 %; 95 %CI-0.84 to-0.12; P = 0.001), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (WMD =-0.71; 95 %CI,-1.14 to-0.27; P = 0.001), and waist to hip ratio (WHR) (WMD =-0.01; 95 %CI,-0.02 to-0.00; P = 0.017). Sumac consumption had no significant effects on weight, body mass index, and waist circumference. Conclusion: We found that Sumac consumption could improve DBP, glycemic indices, and WHR. Also, supplementation of this herb in higher doses or longer durations had more promising effects on FBG, HOMA-IR, and WHR.