Abstract
Present data suggest that obesity is an independent risk factor for cardiovascular diseases. Enhanced lipid peroxidation leading to oxidative modification of lipoproteins may link obesity to cardiovascular morbidity. We investigated the oxidizability and plasma antioxidant vitamins in 22 subjects divided into very obese and lean groups (body mass index 36 ± vs 23 ± 1 kg m−2 respectively). The obese subjects showed a significant elevation in plasma low-density lipoprotein (LDL)-cholesterol and insulin levels. Plasma oxidizability was studied after incubation with a free radical initiator 2, 2'-azobis-2-amidinopropane hydrochloride (AAPH). Lipid peroxidation was measured by malondialdehyde (MDA) and conjugated dienes (CD) generation. Comparing the obese group with the lean group, the rises in the levels of MDA and CD after incubation with AAPH were significantly greater in the former by 23% (MDA; p < 0.05) and 65% (CD; p < 0.01). The levels of plasma carotenoids were also significantly lower (p < 0.05) in obese subjects. In conclusion, in addition to the well-known coronary risk factors (hyperinsulinaemia and increased LDL-cholesterol concentration), obese subjects showed an increased plasma oxidizability and a decrease in plasma antioxidants—the normal balance of which may be of importance in determining the susceptibility of lipoproteins to lipid peroxidation. This mechanism may explain the accelerated atherosclerosis observed in severe obesity.