Effect of altered dietary n-3 fatty acid intake upon plasma lipid fatty acid composition, conversion of [13C]α-linolenic acid to longer-chain fatty acids and partitioning towards β-oxidation in older men

The effect of increased dietary intakes of α-linolenic acid (ALNA) or eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for 2 months upon plasma lipid composition and capacity for conversion of ALNA to longer-chain metabolites was investigated in healthy men (52 (SD 12) years). After a 4-we...

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Published in:British journal of nutrition 2003-08, Vol.90 (2), p.311-321
Main Authors: Burdge, Graham C., Finnegan, Yvonne E., Minihane, Anne M., Williams, Christine M., Wootton, Stephen A.
Format: Article
Language:English
Subjects:
alpha-Linolenic Acid - administration & dosage
alpha-Linolenic Acid - metabolism
Biological and medical sciences
Carbon Dioxide - metabolism
Dietary Fats, Unsaturated - administration & dosage
Dietary Fats, Unsaturated - metabolism
Dietary n-3 polyunsaturated fatty acids
Docosahexaenoic Acids - administration & dosage
Docosahexaenoic Acids - metabolism
Eicosapentaenoic Acid - administration & dosage
Eicosapentaenoic Acid - metabolism
Fatty Acids - blood
Fatty Acids, Unsaturated - administration & dosage
Feeding. Feeding behavior
Fundamental and applied biological sciences. Psychology
Humans
Lipids - blood
Male
Man
Middle Aged
Oxidation-Reduction
Stable isotope
Vertebrates: anatomy and physiology, studies on body, several organs or systems
α-Linolenic acid
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Summary:The effect of increased dietary intakes of α-linolenic acid (ALNA) or eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for 2 months upon plasma lipid composition and capacity for conversion of ALNA to longer-chain metabolites was investigated in healthy men (52 (SD 12) years). After a 4-week baseline period when the subjects substituted a control spread, a test meal containing [U-13C]ALNA (700 mg) was consumed to measure conversion to EPA, docosapentaenoic acid (DPA) and DHA over 48 h. Subjects were then randomised to one of three groups for 8 weeks before repeating the tracer study: (1) continued on same intake (control, n 5); (2) increased ALNA intake (10 g/d, n 4); (3) increased EPA+DHA intake (1·5 g/d, n 5). At baseline, apparent fractional conversion of labelled ALNA was: EPA 2·80, DPA 1·20 and DHA 0·04 %. After 8 weeks on the control diet, plasma lipid composition and [13C]ALNA conversion remained unchanged compared with baseline. The high-ALNA diet resulted in raised plasma triacylglycerol-EPA and -DPA concentrations and phosphatidylcholine-EPA concentration, whilst [13C]ALNA conversion was similar to baseline. The high-(EPA+DHA) diet raised plasma phosphatidylcholine-EPA and -DHA concentrations, decreased [13C]ALNA conversion to EPA (2-fold) and DPA (4-fold), whilst [13C]ALNA conversion to DHA was unchanged. The dietary interventions did not alter partitioning of ALNA towards β-oxidation. The present results indicate ALNA conversion was down-regulated by increased product (EPA+DHA) availability, but was not up-regulated by increased substrate (ALNA) consumption. This suggests regulation of ALNA conversion may limit the influence of variations in dietary n-3 fatty acid intake on plasma lipid compositions.
ISSN:0007-1145
1475-2662
DOI:10.1079/BJN2003901