Effect of dietary essential fatty acids on vitamin A utilization in the rat

After their liver reserves of vitamin A were enhanced to ca. 300 micrograms retinol/g by 5 large daily oral doses of retinyl palmitate, groups of rats (n = 6) were fed a vitamin A-free diet containing 10% corn oil, coconut oil or linseed oil, with or without vitamin E, for a 10-day period. The composition of polyunsaturated fatty acids (PUFA) in liver lipids reflected the dietary composition, with linoleate and linolenate being markedly increased in the livers of rats fed the corn and linseed oil diets, respectively, relative to those fed the coconut oil diet. In contrast, the predominant retinyl ester in the livers of rats on all three diets was retinyl palmitate (greater than 80%), with no diet-related change noted in the relatively small amounts of retinyl linoleate (1-4%) or of retinyl stearate and linolenate (6-11%) present. The depletion of vitamin A from the liver during the 10-day period was slight (less than or equal to 10%) and similar on all three diets. Thus, the ingestion of polyunsaturated fatty acids, with or without vitamin E, did not significantly influence either the mobilization rate or the ester composition of liver vitamin A reserves of rats in good vitamin A status. The relationship of these studies to previous investigations in which PUFA was shown to reduce liver and plasma concentrations of vitamin A is discussed.