Long-chain conversion of [13C]linoleic acid and alpha-linolenic acid in response to marked changes in their dietary intake in men.
We studied the long-chain conversion of [U-13C]alpha-linolenic acid (ALA) and linoleic acid (LA) and responses of erythrocyte phospholipid composition to variation in the dietary ratios of 18:3n-3 (ALA) and 18:2n-6 (LA) for 12 weeks in 38 moderately hyperlipidemic men. Diets were enriched with either flaxseed oil (FXO; 17 g/day ALA, n=21) or sunflower oil (SO; 17 g/day LA, n=17). The FXO diet induced increases in phospholipid ALA (>3-fold), 20:5n-3 [eicosapentaenoic acid (EPA), >2-fold], and 22:5n-3 [docosapentaenoic acid (DPA), 50%] but no change in 22:6n-3 [docosahexanoic acid (DHA)], LA, or 20:4n-6 [arachidonic acid (AA)]. The increases in EPA and DPA but not DHA were similar to those in subjects given the SO diet enriched with 3 g of EPA plus DHA from fish oil (n=19). The SO diet induced a small increase in LA but no change in AA. Long-chain conversion of [U-13C]ALA and [U-13C]LA, calculated from peak plasma 13C concentrations after simple modeling for tracer dilution in subsets from the FXO (n=6) and SO (n=5) diets, was similar but low for the two tracers (i.e., AA, 0.2%; EPA, 0.3%; and DPA, 0.02%) and varied directly with precursor concentrations and inversely with concentrations of fatty acids of the alternative series. [13C]DHA formation was very low (<0.01%) with no dietary influences.
Hussein
Nahed
N
Centre for Nutrition and Food Safety, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom.
Ah-Sing
Eric
E
Wilkinson
Paul
P
Leach
Clare
C
Griffin
Bruce A
BA
Millward
D Joe
DJ
D000328:Adult; D016718:Arachidonic Acid / Q000378:metabolism; D019540:Area Under Curve; D002849:Chromatography, Gas; D004032:Diet; D004281:Docosahexaenoic Acids / Q000378:metabolism; D015118:Eicosapentaenoic Acid / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D006801:Humans; D019787:Linoleic Acid / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010743:Phospholipids / Q000097:blood* / Q000378:metabolism; D012306:Risk; D013997:Time Factors; D017962:alpha-Linolenic Acid / Q000737:chemistry*
D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D010743:Phospholipids; D017962:alpha-Linolenic Acid; D004281:Docosahexaenoic Acids; D016718:Arachidonic Acid; D019787:Linoleic Acid; D015118:Eicosapentaenoic Acid; C026219:docosapentaenoic acid