Why is carbon from some polyunsaturates extensively recycled into lipid synthesis?

Lipids. 2003 Apr;38(4):477-84. doi: 10.1007/s11745-003-1087-8.


We summarize here the evidence indicating that carbon from alpha-linolenate and linoleate is readily recycled into newly synthesized lipids. This pathway consumes the majority of these fatty acids that is not beta-oxidized as a fuel. Docosahexaenoate undergoes less beta-oxidation and carbon recycling than do alpha-linolenate or linoleate, but is it still actively metabolized by this pathway? Among polyunsaturates, arachidonate appears to undergo the least beta-oxidation and carbon recycling, an observation that may help account for the resistance of brain membranes to loss of arachidonate during dietary deficiency of n-6 polyunsaturates. Preliminary evidence suggests that de novo lipid synthesis consumes carbon from alpha-linolenate and linoleate in preference to palmitate, but this merits systematic study. Active beta-oxidation and carbon recycling of 18-carbon polyunsaturates does not diminish the importance of being able to convert alpha-linolenate and linoleate to long-chain polyunsaturates but suggests that a broad perspective is required in studying the metabolism of polyunsaturates in general and alpha-linolenate and linoleate in particular.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Carbon / metabolism*
  • Carbon Isotopes
  • Dietary Fats / metabolism
  • Fatty Acids, Unsaturated / metabolism*
  • Humans
  • Ketones / metabolism
  • Lipids / biosynthesis*
  • Oxidation-Reduction
  • Tissue Distribution


  • Carbon Isotopes
  • Dietary Fats
  • Fatty Acids, Unsaturated
  • Ketones
  • Lipids
  • Carbon