Value of Raisins for Reduction of Oxidative Stress, Endothelial Dysfunction, and Inflammation in Obesity

This study investigated the effects of daily consumption of Thompson seedless raisins on markers of inflammation, oxidative stress and endothelial activation in response to an acute high-fat meal in obese individuals. Seventeen overweight men and women consumed raisins or placebo (264 kcal/d) for 14 d in a randomized cross-over design while following a low-flavonoid, weight-maintenance diet. Four high-fat (53% fat) meals were consumed with the respective treatment pre and post interventions. Measures at fasting, and 2, 3 and 4 hours postprandial included markers of oxidative stress (urinary 8-isoPGF2α; serum Oxygen Radical Absorbance Capacity, ORAC), inflammation (serum C-reactive protein, CRP; interleukin-6, IL-6), endothelial function (serum soluble intercellular adhesion molecule-1, sICAM-1; soluble vascular adhesion molecule-1, sVCAM-1), and metabolic measures (free fatty acids (FFA), triacylglycerol (TAC), glucose, insulin). Urinary 8-isoPGF2α decreased 22% and ORAC increased 3% pre to post interventions combined. Postprandial metabolic responses differed by gender, males surpassed females for several measures: FFA, triacylglycerol, glucose, and sVCAM-1. Neither the meals nor treatment with raisins had any noteworthy influence on fasted measures of inflammation or endothelial dysfunction. Acute high fat meal consumption did not result in evidence of inflammation or oxidative stress in these relatively healthy, overweight individuals. Providing all food in regular pattern reduced measures of oxidative stress. Gender influenced metabolic responses to meals; males had a greater postprandial response in metabolic measures than females.