RESUMO
Flavonoids contained in grapes are potent antioxidants that may protect against oxidative stress and reduce the risk of chronic diseases related with free radical damage. In this study we investigated the effect of daily grape juice supplementation on blood pressure (BP), plasma lipid profiles and the generation of free radicals in 67 healthy volunteers (29 smoker, 38 nonsmokers). The daily 480 ml of grape juice supplementation for 8 weeks resulted in a significant decrease in diastolic BP by 6.5% in smokers and systolic and diastolic BP by 11.2 and 3.7% in non-smokers. Plasma total cholesterol, HDL- and LDL-cholesterol levels in smokers and total cholesterol in non-smokers were significantly increased after the intervention. Plasma triglycerides and conjugated dienes were not affected by grape juice supplementation. Levels of free radical determined by reading the lucigenin-perborate ROS generating sources, decreased significantly by 18% compared to the beginning of the study. The results indicated that the consumption of grape juice may reduce BP and free radical generation in smokers, which was possibly exerted by flavonoids. Our findings suggested that the grape juice has protective effect on chronic disease due to the overproduction of free radical in smokers.