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α-Linolenic acid metabolism in men and women: nutritional and biological implications

Burdge, Graham

Current Opinion in Clinical Nutrition and Metabolic Care: March 2004 - Volume 7 - Issue 2 - p 137-144
Lipid metabolism and therapy
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Purpose of review This review critically evaluates current knowledge of α-linolenic acid metabolism in adult humans based on the findings of studies using stable isotope tracers and on increased dietary α-linolenic acid intake. The relative roles of α-linolenic acid and of longer-chain polyunsaturated fatty acids in cell structure and function are discussed together with an overview of the major metabolic fates of α-linolenic acid. The extent of partitioning towards β-oxidation and carbon recycling in humans is described. The use and limitations of stable isotope tracers to estimate α-linolenic acid desaturation and elongation are discussed. A consensus view of the extent of α-linolenic acid conversion to longer-chain fatty acids in humans is presented. The extent to which increasing dietary α-linolenic acid intake alters the concentrations of longer-chain n-3 fatty acids is described. The biological and nutritional implications of these findings are discussed.

Recent findings Conversion of α-linolenic acid to eicosapentaenoic acid is limited in men and further transformation to docosahexaenoic acid is very low. A lower proportion of α-linolenic acid is used as a substrate for β-oxidation in women compared with men, while the fractional conversion to longer-chain fatty acids is greater, possibly due to the regulatory effects of oestrogen.

Summary Overall, α-linolenic acid appears to be a limited source of longer-chain n-3 fatty acids in man and so adequate intakes of preformed n-3 polyunsaturated fatty acids, in particular docosahexaenoic acid, may be important for maintaining optimal tissue function. Capacity to upregulate α-linolenic acid transformation in women may be important for meeting the demands of the fetus and neonate for docosahexaenoic acid.

Institute of Human Nutrition, University of Southampton, Southampton, UK

Correspondence to Graham Burdge, Institute of Human Nutrition, Biomedical Science Building, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK Tel: +44 2380 594315; fax: +44 2380 594379; e-mail: g.c.burdge@soton.ac.uk

© 2004 Lippincott Williams & Wilkins, Inc.