Effects of Dietary Fats on the Plasma Concentrations of Cholesterol and Free Amino Acids in Rats

Abstract

The effect of dietary fat on the plasma levels of cholesterol and free amino acids was studied for rats fed on a 10 or 20 % casein diet containing cholesterol. Olive, safflower and perilla oil, as well as lard commercially available, were used as the test fats.
The plasma cholesterol level was significantly lower in the rats fed on safflower oil or perilla oil than in the animals fed on lard or olive oil with both the 10 and 20% casein diets. There was no difference in the plasma cholesterol level between the lard and olive oil supplemented diets, nor between the safflower oil and perilla oil supplemented diets. The HDL-cholesterol level in the plasma was higher in the rats fed on safflower oil than in the animals fed on lard, olive oil or perilla oil.
The effect of dietary fat on the free amino acid content of the plasma showed significant differences between the levels of methionine, glycine and tyrosine in both the diets with lard and with perilla oil in the 10% casein diet. In the 20% casein diet, the levels of methionine, leucine, isoleucine, glutamic acid, serine and glycine were significantly different from those with the lard and perilla oil diets. These results indicate that a change in the type of dietary fat will result in a difference in the level of plasma free amino acids.