Effect of Saturated Fat upon Essential Fatty Acid Metabolism of the Rat

Abstract

Two different experiments were conducted using male weanling rats fed fat-free diets supplemented with 1 to 25% of fat. When completely hydrogenated coconut oil (HCO) was the only source of fat, the intake of high-fat diets inhibited growth and reduced caloric efficiencies. When fed diets containing EFA, as 1% of corn oil or 0.5% of ethyl linoleate, increased intakes of HCO allowed greater growth and did not alter the caloric efficiencies of the rats. The ability of EFA-supplemented rats to utilize calories was greater than that of EFA-deficient rats at each level of fat intake. High intakes of HCO promoted the accumulation of polyunsaturated acids in the hearts of both EFA-supplemented and EFA-deficient rats. EFA-deficient rats fed all levels of HCO had equally high concentrations of trienoic acids in their hearts. Rats fed EFA had significantly lower heart trienoic acid content but showed a 20-fold increase in these polyenoic acids when 24.5% of HCO was added to the diet. These studies demonstrate that essential fatty acids are required for the proper utilization of fat calories. Furthermore, high ratios of saturated fat: EFA promote the onset of EFA-deficiency symptoms in the rat.