Dietary lysine and carnitine: relation to growth and fatty livers in rats

Male weanling rats were fed a 72% rice diet containing no detectable carnitine and limiting in threonine and lysine. Such dietary conditions may simulate protein malnutrition in man. Under these conditions growth impairment, anemia, hypoproteinemia, and fatty liver developed. The study focused principally on the fatty liver syndrome which was corrected to varying extents depending on degrees of supplementation with carnitine, lysine, threonine, and appropriate combinations of these nutrients. Such reduction in fatty liver accumulation was accounted for principally by the lowering of triglycerides, but also in part of total cholesterol levels. All the data, which also included monitoring carnitine uptake by the tissues and measurement of plasma triglycerides, were consistent with the view that fatty liver accumulation occurs in amino acid deficient diets because (a) of an impairment in the synthesis of the lipoprotein complex mandatory for triglyceride secretion from the liver and (b) from a deficiency of carnitine needed for the intramitochondrial transport of fatty acids prerequisite for their oxidation.