β-Carotene and α-tocopherol inhibit the development of atherosclerotic lesions in hypercholesterolemic rabbits

Male New Zealand rabbits were made hypercholerolemic by feeding an atherogenic diet (0.5% cholesterol, 3% peanut oil, and 3% coconut oil) with or without antioxidants for 8 weeks. The treatments were IV injection of β-carotene (25 mg/kg BW, twice weekly), dietary α-tocopherol (0.5%), a combination of both, and no added antioxidants (control), β-carotene treatment significantly decreased total and LDL cholesterol concentrations, thoracic atherosclerotic lesion area, and aortic intimai thickness, but had no effects on LDL oxidation ex vivo as compared to control. Dietary a-tocopherol supplementation significantly decreased the susceptibility of LDL to oxidation ex vivo, total atherosclerotic lesion area, and aortic intimai thickness as compared to control. Combination of both antioxidants significantly decreased the susceptibility of LDL to oxidation ex vivo, total atherosclerotic lesion area, and aortic intimai thickness as compared to control, but not β-carotene or α-tocopherol groups. These data suggest that the inhibition of development of atherosclerotic lesions by antioxidants may result from a combination of both antioxidant and nonantioxidant activities. (Supported in part by the Nebraska Agricultural Research Division and Applied Carotenoid Sciences, Inc.).