Casein and soy protein isolate in experimental atherosclerosis: Influence on hyperlipidemia and lipoprotein oxidation

Background/Aims: Nutrients able to modify the susceptibility of lipoprotein s to oxidation and/or reduce the cholesterol levels of blood plasma are imp ortant for prevention and/or treatment of atherosclerosis. The influence of animal and vegetable proteins on hypercholesterolemia and atherogenesis ha s been studied, concerning the mechanisms able to modify the digestion, abs orption and bioavailability of lipids. In this study, the influence of case in and soy protein isolate on lipoprotein oxidation and atherosclerosis pro gression was investigated in cholesterol-fed rabbits. Methods: During 2 mon ths, 20 New Zealand rabbits were fed with diets containing 1% cholesterol a nd 27% casein or 27% soy protein isolate. Blood samples were collected at b aseline, 15, 30, 45 and 60 days of feeding. Results: Casein feeding contrib uted to increasing cholesterol and triglyceride concentrations, lipoprotein oxidation and the area of aorta atherosclerotic lesions. In contrast, the soy protein isolate reduced, when compared to casein, the concentrations of cholesterol and lipid peroxides of beta -VLDL and LDL fractions during the experimental time course, as well as the area of atherosclerotic lesions a t the end of the study. Conclusion: Soy protein isolate, in comparison with casein, promoted a decrease of lipid peroxides, cholesterol and triglyceri de content of atherogenic lipoproteins (beta -VLDL and LDL), which had bene ficial effects over atherosclerosis progression in cholesterol-fed rabbits. Copyright (C) 2001 S. Karger AG, Basel.