Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: April 28, 1996
Publication Date: N/A
Technical Abstract: The influence of dietary arachidonic acid (20:4n-6) on delta-5 desaturation and incorporation of deuterium labeled 20:3n-6 by human subjects was investigated. Adult male subjects (n=4) were fed a high 20:4n-6 diet (HI20:4 diet) containing 1.8 g\day (2.2% of total fat) or a normal 20:4n-6 diet (LOW20:4 diet) containing 0.3 g\day (0.23% of total fat) of 20:4n-6 for 50 days. A mixture containing ethyl esters of 20:3n-6[d4] and an internal standard (18:1n-9[d2]) was then fed to each subject. Conversion of 20:3n-6[d4] to 20:4n-6[d4] was greatly stimulated by the HI20:4 diet. Based on the concentrations of 20:3n-6[d4] and 20:4n-6[d4] in total plasma lipids, conversion was 17.7 +/10.79% (HI20:4 diet) and 2.13 +/- 1.44% (LOW20:4 diet). Comparison of 20:3n-6[d4] and 18:1n-9[d2] data for plasma lipid classes indicated a greater than 2 fold selectivity for incorporation of 20:3n-6[d4] into PL and a greater than two-fold selective incorporation for 18:1n-9[d2] in plasma TG and CE. Data for chylomicron total lipids showed that absorption of the 20:3n-6[d4] ethyl ester was about 20% less than for the 18:1n-9[d2] ethyl ester. The results indicate that the 1.5g/day difference in 20:4n-6 intake simulated the conversion of 20:3n-6[d4] to 20:4n-6[d4] (p<0.006) but did not affect the absorption and incorporation 18:1-d2 and 20:3n-6[d4] into plasma lipids or the relative proportions of the deuterated fatty acids incorporated into plasma lipid classes.