Effect of Oleic and Linoleic Acids on the Absorption of Saturated Fatty Acids in the Chick

Abstract

Palmitic and stearic acids, which are utilized very poorly by the chick when fed singly, are absorbed to a significant degree when fed in a mixture of fatty acids such as hydrolyzed lard. Experiments were conducted with chicks to determine whether oleic and linoleic acids are specifically required for absorption of the saturated fatty acids. Increasing the amount of oleic acid (O) in relation to palmitic acid (P) resulted in a linear increase in absorption of the palmitic acid. A significant improvement was detected with an oleic to palmitic acid ratio (O:P) of 0.1:1. The absorb-ability of palmitic acid was increased to 80% when the O:P ratio was 0.8:1, and maximal absorption of 85 to 90% was obtained with an O:P ratio of 1.34:1. The effect of linoleic acid (L) was less dramatic. The maximal improvement in absorption of palmitic acid was 20% with the highest levels of linoleic acid. Mixtures containing a ratio of linoleic to palmitic acid (L:P) of 1:1 or more were no better than a ratio of L:P of 0.4:1. Palmitic and stearic acids when fed together tended to depress the absorption of each other. In mixtures of these 2 saturated fatty acids, high levels of oleic acid were required for 50% absorption of each of the saturated fatty acids. When linoleic acid was fed with oleic acid and a mixture of the 2 saturated fatty acids, maximal absorption of the saturated fatty acids was obtained with lower levels of both of the unsaturated fatty acids. Oleic acid appears to play a direct role in facilitating the absorption of the saturated fatty acids. It is not known whether this effect is exerted in the lumen or in the mucosal cells of the intestine.