Alpha-tocopherol protects against diet induced atherosclerosis in New Zealand white rabbits

In this study, we asked the question "does alpha-tocopherol supplementation prevent an increase in total plasma cholesterol (TPC) concentration and reduce the deposition of cholesterol in arterial plaques of rabbits fed atherogenic diets?" Isocaloric diets containing 0.1% cholesterol to induce atherosclerosis were enriched in one of three fats: saturated fats (SAT), monounsaturated fats (MONO), or n-6 polyunsaturated fats (POLY). Half of each of the three diets were supplemented with 2,500 IU alpha-tocopherol/kg-diet. Unsupplemented diets contained 25 IU alpha-tocopherol/kg-diet. Rabbits supplemented with alpha-tocopherol had plasma alpha-tocopherol concentrations 10-fold higher and an average TPC concentration 31% lower, P = 0.017, than rabbits fed unsupplemented diets. Among the three fat-fed groups, the difference was greatest for the POLY fat fed group (54%, P = 0.041). POLY fat-fed rabbits without alpha-tocopherol supplementation had plasma HDL cholesterol concentrations that were less than half that of rabbits fed other fats, P < or = 0.0001. In general, differences in mean esterified artery cholesterol concentrations among the three fat-fed groups, with and without alpha-tocopherol supplementation, paralleled differences in TPC concentration among the groups. This study suggests that for rabbits fed high pharmacological doses of alpha-tocopherol, atherosclerosis can be diminished in situations where the plasma cholesterol concentrations are also significantly lower.