Sumac fruit supplementation improve glycemic parameters in patients with metabolic syndrome and related disorders: A systematic review and meta-analysis.

Abstract Background Metabolic syndrome (MetS) is the one of the main causes of mortality worldwide. Several randomized controlled trials (RCTs) have revealed the beneficial effects of sumac (Rhus coriaria) on cardiometabolic risk factors. However, the entirety of the evidence has yet to be summarized in a systematic review. Objective The aim of this systematic review and meta-analysis was to evaluate the effects of sumac on several cardiometabolic risk factors in patients with MetS and related disorders. Methods We reviewed Medline, Scopus, Web of Science and Cochrane CENTRAL for RCTs published from inception to December 2020 evaluating the impact of sumac in adults with MetS or related disorders. Outcome measures included anthropometric measures, glycemic indices, blood lipids, blood pressure and liver enzymes. Pooled effect sizes were reported as standard mean differences (SMDs) and 95% confidence intervals (CIs). Trials were pooled using a random effects model. Results Nine studies enrolling 526 participants met the inclusion criteria for this meta-analysis. Our results indicate that sumac intake significantly decrease fasting blood sugar (FBS) (SMD: −0.28; 95% CI: −0.54, -0.02; I2 = 00.0%), insulin (SMD: −0.67; 95% CI: −0.99, -0.36; I2 = 03.7%), and insulin resistance (measured through the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR)) (SMD: −0.79; 95% CI: −1.24, -0.34; I2 = 50.1%). Sumac intake did not have a significant impact on weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), waist to hip ratio (WHR), HbA1c, total cholesterol (TC), triglycerides (TG), high density lipoproteins (HDL), low density lipoprotein (LDL), systolic blood pressure (SBP), diastolic blood pressure (DBP), aspartate transaminase (AST) and alanine transaminase (ALT). Conclusion Sumac, as an adjuvant therapy, may decrease serum levels of FBS, insulin and HOMA-IR. However, due to high heterogeneity in the included studies, these findings must be interpreted with great caution. Larger, well-designed placebo-controlled clinical trials are still needed to further evaluate the capacity of sumac as a complementary treatment to control MetS risk factors.