Influence of linoleic acid on desaturation and uptake of deuterium-labeled palmitic and stearic acids in humans.

Objectives of this study were to investigate the desaturation of stearic acid (18:0) and palmitic acid (16:0), to determine if differences in their metabolism provide a reasonable explantation for differences in their effect on serum cholesterol levels, and to investigate the affect of linoleic acid on delta 9-desaturase products in man. Deuterium-labeled 16:0 and 18:0 were used to follow the metabolism of these fatty acids in young adult male subjects that were pre-fed diets containing two different levels of linoleic acid. Results indicate that absorption of 16:0 and 18:0 was similar when all components of the mixture used to formulate the deuterated fat mixture were kept above the melting point of tristearin.

Measurement of the metabolic interconversion of deuterium-labeled fatty acids by gas chromatography/mass spectrometry.

An analytical method that was developed to analyze deuterium-labeled fatty acids in human blood has been extended to identify labeled fatty acids from C14 to C24 chain length which are formed by metabolic processes such as desaturation, elongation, or shortening of the labeled fatty acids fed. A new computer and a hardware adder have been utilized to assure reliable data acquisition. Relative standard deviations for the analysis of labeled fatty acids were measured at 0.

Incorporation of trans-8- and cis-8-octadecenoic acid isomers in human plasma and lipoprotein lipids.

Mixtures of deuterium-labeled trans-8, cis-8 and cis-9-octadecenoic acids (8t-18:1, 8c-18:1, 9c-18:1) were fed as triglycerides (TG) to two adult male subjects. Blood samples were collected sequentially over a 48-hour period. Plasma and lipoprotein lipids were separated by thin layer chromatography and analyzed by gas chromatography-mass spectroscopy.