Postprandial oxidative stress is modified by dietary fat: evidences from a human intervention study

International audiencePrevious evidences support the concept that increased oxidative stress may play an important role in the metabolic syndrome (MetS)-related manifestations. Dietary fat quality has been proposed to be critical in oxidative stress and the pathogenesis of the MetS. We investigated whether oxidative stress parameters are affected by diets with different fat quantity and quality during the postprandial state in subjects with the MetS. Patients were randomly assigned to one of four isoenergetic diets distinct in fat quantity and quality: high-saturated fatty acid (HSFA); high-monounsaturated fatty acid (HMUFA) and two low-fat, high complex carbohydrate (diets, supplemented with 1.24 g/day of long chain n-3 polyunsaturated fatty acid (LFHCC n-3) or with placebo (LFHCC) for 12 weeks. HMUFA diet enhanced postprandial reduced glutathione levels and the glutathione/oxidized glutathione ratio, compared to the other three diets. In addition, after the HMUFA diet postprandial lipid peroxides levels, protein carbonyls concentration, superoxide dismutase activity and plasma hydrogen peroxide plasma levels were lower compared to subjects adhering to the HSFA diet. Both LFHCC diets had an intermediate effect relative to the HMUFA and HSFA diets. Our data support the notion that the HMUFA diet improves postprandial oxidative stress in patients with the MetS. These findings suggest that the postprandial state is important for understanding possible cardio-protective effects associated with monounsaturated dietary fat particularly in subjects with the MetS (NCT00429195