Beneficial Effect of Pistachio Consumption on Glucose Metabolism, Insulin Resistance, Inflammation, and Related Metabolic Risk Markers: A Randomized Clinical Trial

OBJECTIVE: To examine whether a pistachio-rich diet reduces the prediabetes stage and improves its metabolic risk profile. RESEARCH DESIGN AND METHODS: Prediabetic subjects were recruited to participate in this Spanish randomized clinical trial between 20 September 2011 and 4 February 2013. In a crossover manner, 54 subjects consumed two diets, each for 4 months: a pistachio-supplemented diet (PD) and a control diet (CD). A 2-week washout period separated study periods. Diets were isocaloric and matched for protein, fiber, and saturated fatty acids. A total of 55% of the CD calories came from carbohydrates and 30% from fat, whereas for the PD, these percentages were 50 and 35%, respectively (including 57 g/day of pistachios). RESULTS: Fasting glucose, insulin, and HOMA of insulin resistance decreased significantly after the PD compared with the CD. Other cardiometabolic risk markers such as fibrinogen, oxidized LDL, and platelet factor 4 significantly decreased under the PD compared with the CD (P < 0.05), whereas glucagon-like peptide-1 increased. Interleukin-6 mRNA and resistin gene expression decreased by 9 and 6%, respectively, in lymphocytes after the pistachio intervention (P < 0.05, for PD vs. CD). SLC2A4 expression increased by 69% in CD (P = 0.03, for PD vs. CD). Cellular glucose uptake by lymphocytes decreased by 78.78% during the PD (P = 0.01, PD vs. CD). CONCLUSIONS: Chronic pistachio consumption is emerging as a useful nutritional strategy for the prediabetic state. Data suggest that pistachios have a glucose- and insulin-lowering effect, promote a healthier metabolic profile, and reverse certain metabolic deleterious consequences of prediabetes.