Pistachios and cardiometabolic risk factors: a systematic review and meta-analysis of randomized controlled clinical trials

Background: Previous experimental studies have reported that pistachios can elicit positive effects on lipid profile, blood pressure, and inflammation; however, a meta-analysis of the available evidence has yet to be performed. Objective: the aim of this study was to conduct systematic review and meta-analysis of the effect of pistachio enriched diets on cardiometabolic risk factors, such as weight, BMI, blood pressure, serum lipids, blood glucose, and inflammatory biomarkers. Design: A literature search was carried out for RCTs in medical databases, including PubMed/MEDLINE, Scopus, and Cochrane databases, with no time limitation up to August 2019, and conducted in accordance with the Preferred Reporting Items of Systematic Reviews and Meta-Analysis guidelines. Results: 11 RCTs, with 506 participants, that reported the effect of pistachios consumption on cardiometabolic risk factors were included in this systematic review and meta-analysis. Our findings indicated that pistachios consumption significantly reduced FBS (WMD: -3.73, 95 % CI: -6.99, -0.46, I ² = 99 %), TC/HDL (WMD: -0.46, 95 % CI: -0.76, -0.15, I ² = 95 %), LDL/HDL (WMD: -0.24, 95 % CI: -0.38, -0.11, I ² = 96 %), HbA1C (WMD: -0.14, 95 % CI: -0.26, -0.02, I ² = 60 %), Insulin (WMD: -2.43, 95 % CI: -4.85, -0.001, I ² = 58 %), SBP (WMD: -3.10, 95 % CI: -5.35, -0.85, I ² = 63 %), and MDA (WMD: -0.36, 95 % CI: -0.49, -0.23, I ² = 0%). Importantly, we did not observe adverse effects of pistachios consumption on BMI or blood pressure. Conclusion: This systematic review and meta-analysis demonstrates that pistachios consumption can elicit a beneficial effect on some cardiometabolic risk factors. All previous clinical studies are well designed but some points have still remained unclear including the effects of different pistachios dosages on cardio metabolic risk factors and efficacy of pistachios consumption in preventing endothelial dysfunction. Further examination is required to determine the effect of pistachios consumption on further endothelial function risk factors.