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United States Department of Agriculture

Agricultural Research Service

Title: Influence of Dietary Arachidonic Acid on Human Metabolism of Deuterium Labeled Dihomo-Y-Linolenic Acid (20:3n-6) and Arachidonic Acid (20:4n-6)

item Emken, Edward
item Adlof, Richard
item Duval, Sandra
item Nelson, Gary

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 7, 1996
Publication Date: N/A

Technical Abstract: The metabolism of deuterium-labeled 20:4n-6 and 20:3n-6 was investigated in male subjects fed diets of 1.8 g\day (2.2% of total fat) and 0.3 g\day (0.23% of total fat) of 20:4n-6 for 50 days. Subjects were dosed with mixtures of ethyl 20:3n -6[d4] and ethyl 18:1n-9[d2] or of ethyl 20:4n-6 and ethyl 18:1n-9[d2] and blood samples were drawn at 0, 4, 6, 8, 12, 24, 48, 72 hr. Methyl esters of plasma total lipid (TL), triglyceride (TG), phospholipids (PL), and cholesterol ester (CE) were analyzed by GC-MS. Conversion of 20:3n-6[d4] was increased by the HI20:4 diet compared to the LOW20:4 diet. Conversion of 20:3n-6[d4] to 20:4n-6[d4] was 17.6+/-0.78% for subjects fed the HI20:4 diet compared to 1.8+/-1.04% for the LOW20:4 diet subjects. Data for chylomicron total lipids show that 20:3n-6[d4] and 20:4n-6 ethyl ester were significantly less-well absorbed than ethyl 9c-18:1n-9[d2] and absorption was not significantly influenced by the 20:4n-6 content of the diets. The percent of deuterated 16:2n-6, 18:2n-6, 18:3n-6 retroconversion products from 20:3n-6[d4] and 20:4n-6[d4] in total plasma lipids was low and not influenced by diet. Comparison of 20:3n-6[d4] and 20:4n-6[d4] to 18:1n-9[d2] data show almost a 2 fold selectivity for incorporation of 20:3n -6[d4] into PL compared to 18:1n-9[d2]. Less 20:3n-6[d4] and 20:4n-6[d4] than 18:1n-9[d2] were incorporated into TG and CE. Diet did not significantly influence the selectivity for deuterated fatty acid incorporation into lipid classes.

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