Effects of Oral L-carnitine Supplementation on in Vivo Long-Chain Fatty Acid Oxidation in Healthy Adults

Metabolism. 2002 Nov;51(11):1389-91. doi: 10.1053/meta.2002.35181.


Despite an abundance of literature describing the basic mechanisms of action of L-carnitine metabolism, there remains some uncertainty regarding the effects of oral L-carnitine supplementation on in vivo fatty acid oxidation in normal subjects under normal conditions. It is well known that L-carnitine normalizes the metabolism of long-chain fatty acids in cases of carnitine deficiency. However, it has not yet been shown that L-carnitine influences the metabolism of long-chain fatty acids in subjects without disturbances in fatty acid metabolism. Therefore, we investigated the effects of oral L-carnitine supplementation on in vivo long-chain fatty acid oxidation by measuring 1-[(13)C] palmitic acid oxidation in healthy subjects before and after L-carnitine supplementation (3 x 1 g/d for 10 days). We observed a significant increase in (13)CO(2) exhalation. This is the first investigation to conclusively demonstrate that oral L-carnitine supplementation results in an increase in long-chain fatty acid oxidation in vivo in subjects without L-carnitine deficiency or without prolonged fatty acid metabolism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Blood Glucose / metabolism
  • Breath Tests
  • Carbon Dioxide / analysis
  • Carbon Isotopes
  • Carnitine / administration & dosage*
  • Carnitine / pharmacokinetics
  • Carnitine / pharmacology*
  • Fatty Acids / metabolism*
  • Female
  • Glycated Hemoglobin A / metabolism
  • Humans
  • Lipids / blood
  • Male
  • Oxidation-Reduction
  • Reference Values


  • Blood Glucose
  • Carbon Isotopes
  • Fatty Acids
  • Glycated Hemoglobin A
  • Lipids
  • Carbon Dioxide
  • Carnitine