A comparison of the metabolism of elaidic, oleic, palmitic, and stearic acids in the rat

Robert H Coots

doi:10.1016/s0022-2275(20)40223-8

Abstract

A comparison has been made of the metabolism of 1-C14-labeled oleic, elaidic, palmitic, and stearic acids in the rat. Each acid was fed as a component of randomly rearranged soybean oil. All the acids were more than 96% absorbed. The rate of catabolism and the extent to which elaidic acid was excreted in the respiratory CO2 were essentially the same as those of oleic acid and both of these acids were similar to palmitic acid. Oleic, elaidic, and palmitic acids were catabolized to CO2 to a greater extent than was stearic acid. Elaidic acid seemed to be incorporated into the lymph phospholipids to a slightly greater extent than was oleic acid during the peak of absorption; otherwise, elaidic acid was similar to oleic acid in its absorption and distribution among the lymph lipids. Stearic acid was incorporated into the lymph phospholipids to a considerably greater degree (~8%) than were the other acids (~2–3%). The major transport of each fatty acid was via the lymph glycerides, being ~90% for stearic acid and ~97% for the other acids.

Highlights

The present paper describes such a comparison between oleic and elaidic acids with reference to palmitic and stearic acids studied under the same experimental conditions
The evidence is clear that the animal is capable of metabolizing trans fatty acids such as elaidic acid
The four experimental fats used in this study consisted of soybean oil labeled with radioactive oleic, elaidic, palmitic, or stearic acid

Summary

MATERIALS AND METHODS

THE METABOLISM of the saturated fatty acids has been thoroughly studied and the catabolic fate of the carbon chain of these acids is known. 1-CI4-Labeled palmitic, stearic, and oleic acids were prepared chemically by decarboxylation of the unlabeled acid using a procedure similar to that of Anker [7] and recarboxylation via the Grignard reaction. Elaidic acid was prepared by SO, isomerization of the purified oleic a ~ i d - 1 - C '(~8). This procedure produces no detectable positional isomers. The four experimental fats used in this study consisted of soybean oil labeled with radioactive oleic, elaidic, palmitic, or stearic acid. Sucrose Non-fat dry milk solids Vitamin mix (in sucrose)* Salt Mix U.S.P. 14 Water Fat

Experimental Diet

Oleic Elaidic Palmitic Stearic

Stearic Acid Group*

Sterol Esters