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Metabolism in humans of cis ‐12, rans ‐15‐octadecadienoic acid relative to palmitic, stearic, oleic and linoleic acids
Author(s) -
Emken E. A.,
Rohwedder W. K.,
Adlof R. O.,
Rakoff H.,
Gulley R. M.
Publication year - 1987
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02540365
Subject(s) - chemistry , chromatography , stearic acid , phosphatidylcholine , lecithin , oleic acid , linoleic acid , fatty acid , biochemistry , organic chemistry , phospholipid , membrane
Mixtures of triglycerides containing deuterium‐labeled hexadecanoic acid (16∶0), octadecanoic acid (18∶0), cis ‐9‐octadecenoic acid (9c–18∶1), cis ‐9, cis ‐12‐octadecadienoic acid (9c, 12c–18∶2) and cis ‐12, trans ‐15‐octadecadienoic acid (12c,15t–18∶2) were fed to two young‐adult males. Plasma lipid classes were isolated from samples collected periodically over 48 hr. Incorporation and turnover of the deuterium‐labeled fats in plasma lipids were followed by gas chromatography‐mass spectrometry (GC‐MS) analysis of the methyl ester derivatives. Absorption of the deuterated fats was followed by GC‐MS analysis of chylomicron triglycerides isolated by ultracentrifugation. Results were the following: (i) endogenous fat contributed about 40% of the total fat incorporated into chylomicron triglycerides; (ii) elongation, desaturation and chain‐shortened products from the deuterated fats were not detected; (iii) the polyunsaturated isomer 12c,15t–18∶2 was metabolically more similar to saturated and 9c–18∶1 fatty acids than to 9c,12c–18∶2 (iv) relative incorporation of 9c,12c–18∶2 into phospholipids did not increase proportionally with an increase of 9c,12c–18∶2 in the mixture of deuterated fats fed; (v) absorption of 16∶0, 18∶0, 9c–18∶1, 9c,12c–18∶2 and 12c,15t–18∶2 were similar; and (vi) data for the 1‐ and 2‐acyl positions of phosphatidylcholine and for cholesteryl ester fractions reflected the known high specificity of phosphatidylcholine acyltransferase and lecithin:cholesteryl acyltransferase for 9c,12c–18∶2. These results illustrate that incorporation of dietary fatty acids into human plasma lipid classes is selectively controlled and that incorporation of dietary 9c,12c–18∶2 is limited. These results suggest that nutritional benefits of diets high in 9c,12c–18∶2 may be of little value to normal subjects and that the 12c,15t–18∶2 isomer in hydrogenated fat is not a nutritional liability at the present dietary level.