The effect of pistachio supplementation on metabolic syndrome and its components in adults: a systematic review and meta-analysis of randomized controlled trials

Context Several observational and experimental studies have been conducted to evaluate the effects of pistachio intake on metabolic syndrome (MetS); however, the results are inconsistent. Objective This systematic review and meta-analysis were performed on data from randomized controlled trials (RCTs) to determine the effect of pistachio consumption on MetS components. Data sources The PubMed, Scopus, Google Scholar and Web of Science databases were searched from 1986 to 2021. Study selection English-language RCTs on pistachio intake were included that provided outcomes on hypertension, hyperglycemia, hypertriglyceridemia, and high-density lipoprotein (HDL). Data extraction Results are presented as pooled mean differences (MDs) between intervention and control groups with 95%CI reported for each of the components. Results Seventeen RCTs including 940 adults met the inclusion criteria for this systematic review and meta-analysis. Pistachio supplementation significantly reduced systolic blood pressure (BP; MD, -2.89 mmHg, 95%CI: -4.11 to -1.67; P < 0.001), triglycerides (MD, -16.76 mg/dL, 95%CI: -16.89 to -16.64; P < 0.001), fasting blood glucose (MD, -3.62 mg/dL, 95%CI: -6.45 to -0.8; P < 0.001,) and increased HDL (MD, 1.43 mg/dL, 95%CI: 1.39 to 1.47; P < 0.001) levels. However, there were not observed considerable changes in waist circumference, diastolic BP, and body mass index. Conclusion The results of this research show that pistachio consumption could improve some MetS components, including systolic blood pressure, triglyceride, fasting blood glucose, and HDL levels, without affecting anthropometric indices and diastolic BP.