Alpha-linolenic acid metabolism in men and women: nutritional and biological implications

Curr Opin Clin Nutr Metab Care. 2004 Mar;7(2):137-44. doi: 10.1097/00075197-200403000-00006.


Purpose of review: This review critically evaluates current knowledge of alpha-linolenic acid metabolism in adult humans based on the findings of studies using stable isotope tracers and on increased dietary alpha-linolenic acid intake. The relative roles of alpha-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 alpha-linolenic acid. The extent of partitioning towards beta-oxidation and carbon recycling in humans is described. The use and limitations of stable isotope tracers to estimate alpha-linolenic acid desaturation and elongation are discussed. A consensus view of the extent of alpha-linolenic acid conversion to longer-chain fatty acids in humans is presented. The extent to which increasing dietary alpha-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 alpha-linolenic acid to eicosapentaenoic acid is limited in men and further transformation to docosahexaenoic acid is very low. A lower proportion of alpha-linolenic acid is used as a substrate for beta-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, alpha-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 alpha-linolenic acid transformation in women may be important for meeting the demands of the fetus and neonate for docosahexaenoic acid.

Publication types

  • Review

MeSH terms

  • Carbon Isotopes
  • Eicosapentaenoic Acid / metabolism
  • Energy Metabolism
  • Fatty Acids, Unsaturated / metabolism
  • Fatty Acids, Unsaturated / physiology
  • Female
  • Humans
  • Male
  • Nutritional Requirements
  • Oxidation-Reduction
  • Sex Characteristics
  • alpha-Linolenic Acid / administration & dosage
  • alpha-Linolenic Acid / metabolism*
  • alpha-Linolenic Acid / physiology


  • Carbon Isotopes
  • Fatty Acids, Unsaturated
  • alpha-Linolenic Acid
  • Eicosapentaenoic Acid
  • docosapentaenoic acid