Incorporation and disappearance of trans fatty acids in rat tissues.

An investigation was undertaken to study the rate of incorporation and disappearance of trans isomers of octadecenoic and octadecadienoic acids from different tissues of rats fed 15% fat diets containing trans fatty acids for 3 months. At the end of 3 months some of the animals were killed and the remaining animals were changed over to a diet containing only trace amounts of trans fatty acids. Thereafter, representative animals were killed at 2, 4, 8, and 12 weeks. The fatty acid composition of tissue lipids was measured by gas liquid chromatography. Trans octadecenoate was primarily incorporated into phospholipids and triglycerides of plasma, liver, kidney, heart, adipose tissue, and red blood cells. Trans isomers of octadecadienoate accumulated in triglycerides of plasma, liver, kidney, heart, and adipose tissue while only small amounts accumulated in tissue phospholipids and cholesteryl esters. After removal of trans fatty acids from the diet, the time of disappearance of trans isomers of octadecenoate and octadecadienoate from tissues varied. With the exception of adipose tissue, 8 weeks after the trans fatty acid diet was discontinued, only negligible amounts of trans fatty acids were present in rat tissues, demonstrating that tissues studied can metabolize trans fatty acids.