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Effect of dietary arachidonic acid on metabolism of deuterated linoleic acid by adult male subjects
Author(s) -
Emken E. A.,
Adlof R. O.,
Duval S. M.,
Nelson G. J.
Publication year - 1998
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/s11745-998-0230-x
Subject(s) - linoleic acid , chemistry , arachidonic acid , triglyceride , phospholipid , lipidology , metabolism , medicine , clinical chemistry , fatty acid , cholesterol , endocrinology , biochemistry , biology , membrane , enzyme
The influence of dietary supplementation with 20:4n−6 on uptake and turnover of deuterium‐labeled linoleic acid (18:2n−6[ d 2 ]) in human plasma lipids and the synthesis of desaturated and elongated n−6 fatty acids from 18:2n−6[ d 2 ] were investigated in six adult male subjects. The subjects were fed either a high‐arachidonic acid (HIAA) diet containing 1.7 g/d or a low‐AA (LOAA) diet containing 0.21 g/d of AA for 50 d. Each subject was then dosed with about 3.5 g of 18:2n−6[ d 2 ] as the triglyceride (TG) at 8:00 a.m. , 12:00, and 5:00 p.m. The total 18:2n−6[ d 2 ] fed to each subject was about 10.4 g and is approximately equal to one‐half of the daily intake of 18:2n−6 in a typical U.S. male diet. Nine blood samples were drawn over a 96‐h period. Methyl esters of plasma total lipid (TL), TG, phospholipid, and cholesterol ester were analyzed by gas chromatography‐mass spectroscopy. Dietary 20:4n−6 supplementation did not affect uptake of 18:2n−6[ d 2 ] in plasma lipid classes over the 4‐d study period nor the estimated half‐life of 24–36 h for 18:2n−6[ d 2 ]. The percentages of major deuterium‐labeled desaturation and elongation products in plasma TL, as a percentage of total deuterated fatty acids, were 1.35 and 1.34% 18:3n−6[ d 2 ]; 0.53 and 0.50% 20:2n−6[ d 2 ]; 1.80 and 0.92% 20:3n−6[ d 2 ] and 3.13 and 1.51% 20:4n−6[ d 2 ] for the LOAA and HIAA diet groups, respectively. Trace amounts (<0.1%) of the TL concentration data for both 20:3n−6[ d 2 ] and 20:4n−6[ d 2 ] were 48% lower ( P <0.05) in samples from the HIAA diet group than in samples from the LOAA diet group. For a normal adult male consuming a typical U.S. diet, the estiamted accumulation in plasma TL of 20:4n−6 synthesized from 20 g/d (68 mmole) of 18:2n−6 is 677 mg/d (2.13 mmole). Dietary supplementation with 1.5 g/d of 20:4n−6 reduced accumulation of 20:4n−6 synthesized from 20 g/d of 18:2n−6 to about 326 mg/d (1.03 mmole).