Interaction of Dietary Protein and Fat on Plasma Cholesterol and Amino Acid Levels, Fatty Acid Desaturation, and Prostacyclin Production in Exogenous Hypercholesterolemic Rats

Abstract

The interaction of dietary protein, casein (CAS) or soybean protein (SOY), and fats (perilla oil high in α-linolenic acid or safflower oil high in linoleic acid) on various lipid parameters and plasma amino acids was studied in a rat model sensitive to dietary cholesterol (exogenous hypercholesterolemic (ExHC) rats). The hypolipidemic effect of SOY in comparison with that of CAS was confirmed in this model irrespective of the fat source. Thus, the hypocholesterolemic effect of SOY appeared to be intrinsic. However, the effects of dietary protein on the fatty acid composition of tissue phospholipids, Δ6 desaturase activity in liver microsomes and aortic prostacyclin production were marginal. An analysis of plasma amino acids suggests a regulatory role of specific amino acid(s) in the hypocholesterolemic effect of SOY.