Scientific Study

BACKGROUND AND AIMS: Knowledge of the effect of nut consumption on metabolic syndrome (MetS) components is limited. We assessed the effects of nut intake on adiposity; serum lipids; insulin resistance; and inflammatory biomarkers in patients with MetS. METHODS AND RESULTS: In a randomized; parallel-group; 12-week feeding trial; 50 patients with MetS were given recommendations for a healthy diet with or without supplementation with 30g/day of raw nuts (15g walnuts; 7.5g almonds and 7.5g hazelnuts) (Nut and Control diet groups; respectively). Adiposity measures; serum lipids; insulin; Homeostasis Model Assessment (HOMA); interleukin-6 (IL-6) and other inflammatory biomarkers; and 48-h fecal fat were determined basally and at study's completion. Moderate weight loss; decreased adiposity; and lower blood pressure occurred similarly after both diets. The Control; but not the Nut diet; was associated with significant (P<0.05) reduction of LDL-cholesterol; with mean changes of -0.36 versus -0.13mmol/L; respectively (between-group differences; P=0.154). The Nut diet reduced fasting insulin by 2.60muU/mL (95% CI; -4.62 to -0.59) and HOMA-insulin resistance by 0.72 (-1.28 to -0.16) (P<0.05 versus Control diet; both). Among inflammatory markers; the Nut diet resulted in changes of median plasma IL-6 of -1.1ng/L (-2.7 to -0.1; P=0.035 versus Control diet); but adjustment for weight loss attenuated the significance of the association. Stool fat decreased with the Control diet and slightly increased with the Nut diet (P<0.05 for between-group differences). CONCLUSION: Patients with MetS show decreased lipid responsiveness but improved insulin sensitivity after daily intake of 30g of mixed nuts.