α-Linolenic acid prevents the hypercholesteremic effects of cholesterol addition to a corn oil diet

Abstract

The effects of three different diets to which cholesterol with or without cholic acid were compared for their hyperlipemic effect in C57BL 6J mice. The addition of 1% cholesterol and 0.5% cholic acid (CC) to a standard Laboratory Rodent Chow diet that contains 4.5% total mixed fat, had little effect on serum lipids. In contrast, addition of CC to a AIN76A diet that contains 5% corn oil and low levels of α-linolenic acid (18:3 ϵ, α LNA) resulted in a 76% increase in total plasma cholesterol levels. The fat content of a semipurified (ANFAT) hypercholesteremic diet (ANFAT + CC) had to be raised to 18% lard to obtain a similar elevation in plasma total lipid levels. Neither dietary corn oil, ANFAT, nor CC alone caused an increase in plasma cholesterol and total lipid levels. The addition of α LNA to the AIN76A diet resulted in a decrease in plasma cholesterol and total lipid concentrations. We conclude that the addition of CC to AIN76A diet unmasked an α-linolenic acid insufficiency in this diet, leading to elevation of plasma cholesterol levels. The addition of α LNA restored the dietary lipid balance and reestablished a normocholesteremic level.