Experimental atherosclerosis in swine: Effect of dietary protein and high fat

Abstract

Two groups of pigs each consisting of 6 animals were fed for 18 months on isocaloric amounts of an experimental diet with a high fat content and cholesterol but with widely different levels of protein (5% vs. 25% by weight of the diet). In addition, a third group consisting of 4 animals was maintained on normal stock diet to serve as control. Animals of the low protein group showed the maximal intimal surface area involvement with atherosclerotic lesions in the aorta and coronary arteries, and also the most severe among the three groups. No significant differences were noted in the extent and severity of lesions between the high protein-high fat fed animals as compared with the high protein-low fat fed controls. Lesions of the low protein group had a higher cholesterol content and a raised cholesterol:phospholipid ratio than those in the other two groups. Extremely low levels of dietary proteins seem to have had a promotive effect on the induction of atherosclerotic lesions by an atherogenic diet, whereas adequate levels of dietary proteins have had a protective influence. The precise mechanism by which varying levels of dietary proteins have such effects is not understood. It may possibly be related to the aberrations of lipid metabolism induced by extremely low levels of dietary proteins.