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

• Published in: Biochimica et biophysica acta Vol. 1170; no. 2; pp. 173 - 181
• Main Authors: Emken, Edward A., Adlof, Richard O., Rohwedder, William K., Gulley, R.Michael
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 13.10.1993; Elsevier
• Subjects: Absorption; Adult; analysis; Biological and medical sciences; blood; Chain-shortening; chemistry; Chylomicrons; Chylomicrons - blood; Desaturation; Deuterium; dietary fat; Dietary Fats, Unsaturated; Dietary Fats, Unsaturated - pharmacology; etiology; Fatty Acid Desaturases; Fatty Acid Desaturases - metabolism; Fatty Acids, Unsaturated; Fatty Acids, Unsaturated - analysis; Fundamental and applied biological sciences. Psychology; Human; Humans; Hypercholesterolemia; Hypercholesterolemia - etiology; Intestinal Absorption; isotope labeling; Linoleic Acid; Linoleic Acids; Linoleic Acids - pharmacology; lipid metabolism; Lipids; Lipids - blood; Lipids - chemistry; Lipids. Glycolipids; Male; men; metabolism; Metabolisms and neurohumoral controls; nutrient uptake; Oleic Acid; Oleic Acids; Oleic Acids - analysis; Palmitic Acid; Palmitic Acids; Palmitic Acids - analysis; Palmitic Acids - chemistry; Palmitic Acids - metabolism; pharmacology; Phosphatidylcholines; Phosphatidylcholines - blood; Saturated fatty acid; stearic acid; Stearic Acids; Stearic Acids - analysis; Stearic Acids - chemistry; Stearic Acids - metabolism; Stearoyl-CoA Desaturase; Temperature; Time Factors; Triglycerides; Triglycerides - blood; Triglycerides - pharmacology; Vertebrates: anatomy and physiology, studies on body, several organs or systems; young adults; Deuterium; Human; FFA; Chain-shortening; CE; RSD; PUFA; MS; SAT; TLC; GC-MS; Absorption; PC; TG; Saturated fatty acid; PE; P/S; Chylo; GC; Desaturation; In vivo; Diet; Stearic acid; Metabolism; Palmitic acid; Fatty acids; Comparative study; Blood
• ISSN: 0005-2760; 0006-3002; 1879-145X; 1878-2434
• DOI: 10.1016/0005-2760(93)90068-K

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 explanation for differences in their effect on serum cholesterol levels, and to investigate the affect of linoleic acid on Δ 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. The percent of 18:0 desaturated to 9 c-18:1 was higher than the percent of 16:0 desaturated to 9 c-16:1 (9.2% vs. 3.9%). The subject-to-subject variability suggests that differences in ability to desaturate saturated fatty acids may be related to the variability observed in response of serum cholesterol levels to dietary saturated fatty acids. Data for the distribution of 16:0 and 18:0 between triacylglycerol and phosphatidylcholine (PC) was markedly different. Based on PC data, phospholipid acyltransferase selectivity was about 2-fold higher for 18:0 than for 16:0. A 2-fold difference in the linoleic acid content of the pre-fed diets had little influence on desaturation or distribution of 16:0 and 18:0 between plasma lipid classes. A deuterium isotope effect was estimated to reduce Δ 9-desaturase enzyme activity by 30–50%.