Is L-Carnitine sold here for research use only, and is it an approved drug?

The L-carnitine supplied by Peptigo is for research use only (RUO) and is not intended for human or veterinary use, diagnosis, or treatment. Note that a pharmaceutical form, levocarnitine, is an approved prescription drug for carnitine deficiency in some jurisdictions; however, the RUO material described here is not that product and carries no usage directions or health claims.

Is L-Carnitine a peptide?

No. L-Carnitine is a small quaternary ammonium compound derived from the amino acids lysine and methionine (IUPAC: (3R)-3-hydroxy-4-(trimethylazaniumyl)butanoate). It has no peptide bonds and is not a peptide, so it has no amino-acid sequence.

What is L-Carnitine's role in metabolism according to research?

Researchers characterize L-carnitine as an obligatory cofactor in the mitochondrial carnitine shuttle, where CPT1, carnitine-acylcarnitine translocase, and CPT2 move long-chain fatty acids into the mitochondrial matrix for beta-oxidation. This is a reported biochemical mechanism, not a health benefit.

What did studies report about L-Carnitine and cardiovascular outcomes?

The evidence is mixed. A 2013 meta-analysis of acute-MI trials reported reductions in mortality, ventricular arrhythmias, and angina, but it was criticized for the quality of included studies. Separately, researchers reported that gut-microbiota metabolism of L-carnitine produces TMAO, a metabolite associated with atherosclerosis in animal models. These are research findings only.

What dosing has been used in L-Carnitine studies?

As reported in studies (not as usage directions): pharmacokinetic work used a single oral 2.0 g dose; cardiac secondary-prevention trials used roughly 2-6 g/day; and exercise-recovery trials used 1-3 g/day. Oral bioavailability is low (~15% per the levocarnitine label).

L-Carnitine Dosage, Half-Life & Research

L-Carnitine is a naturally occurring quaternary ammonium compound (an amino-acid derivative, not a peptide) synthesized in the body from lysine and methionine and obtained from the diet, chiefly red meat.¹ In research models it is characterized as an obligatory cofactor for mitochondrial long-chain fatty-acid oxidation, where it shuttles acyl groups across the inner mitochondrial membrane.² It is supplied to Canadian customers strictly for research use only (RUO); the material described here is not for human or veterinary use, and nothing below should be read as usage directions.¹ Note that the body of evidence is mixed: while a meta-analysis of acute-MI trials reported reduced mortality,⁴ separate studies reported that gut-microbiota metabolism of L-carnitine generates the pro-atherogenic metabolite TMAO.⁵

Structure

Sequence & identity

Not a peptide · C₇H₁₅NO₃ · 161.20 g/mol · quaternary ammonium / amino-acid derivative

Structure and identity per PubChem CID 10917 (InChIKey PHIQHXFUZVPYII-ZCFIWIBFSA-N); IUPAC name (3R)-3-hydroxy-4-(trimethylazaniumyl)butanoate.¹

What the research shows

Mechanisms studied

Researchers describe L-carnitine as the rate-defining substrate of the mitochondrial "carnitine shuttle." In this pathway, carnitine palmitoyltransferase 1 (CPT1) on the outer mitochondrial membrane is reported to transfer a long-chain acyl group from acyl-CoA onto carnitine to form acylcarnitine; carnitine-acylcarnitine translocase moves it across the inner membrane, and CPT2 regenerates acyl-CoA inside the matrix for β-oxidation.² CPT1 is reported to be the principal regulatory step, inhibited by malonyl-CoA, linking carnitine-dependent fat oxidation to overall energy and glucose status.² Investigators have also reported that intestinal microbiota convert dietary L-carnitine to trimethylamine and ultimately trimethylamine-N-oxide (TMAO), a separate, microbiome-dependent metabolic route observed to accelerate atherosclerosis in mouse models.⁵

Reported in studies

Dosing in the research literature

The figures below summarise regimens as reported in published research — they are not recommendations or directions for use.

Source / model	Regimen reported	Notes
Cao et al., Clin Invest Med 2009 ³	Single oral 2.0 g dose of liquid L-carnitine in 12 healthy volunteers (pharmacokinetic study).	Reported for RUO context only, not usage directions. Oral bioavailability of L-carnitine is low; the label-reported absolute bioavailability is ~15% for tablets/solution.⁶
DiNicolantonio et al., Mayo Clin Proc 2013 ⁴	Across 13 pooled secondary-prevention trials in acute MI (N=3629), study-administered L-carnitine spanned roughly 2-6 g/day (oral and/or intravenous, varying by trial).	Doses as reported in the source trials; the meta-analysis was later criticized for methodological flaws in the included studies. Not a dosing recommendation.
Exercise-recovery meta-analysis (Yarizadh et al., PMID 32154768) ⁷	Study-reported regimens ranged from 1-3 g/day, from single doses to ~8-week chronic administration.	As reported in studies of exercise-induced muscle damage; individual-trial results were mixed. Not usage directions.

Research use only. Peptigo products are sold to qualified researchers for laboratory use. This information summarises published research for reference and is not medical advice, a dosing recommendation, or directions for human or animal use.

Reported in studies

Effects observed in research

In acute-myocardial-infarction trials pooled by DiNicolantonio et al., L-carnitine was associated with a 27% reduction in all-cause mortality (OR 0.73; 95% CI 0.54-0.99), a 65% reduction in ventricular arrhythmias (RR 0.35; 95% CI 0.21-0.58) and a 40% reduction in angina (RR 0.60; 95% CI 0.50-0.72), with no significant effect on heart failure or reinfarction; the authors themselves called for larger trials and the analysis drew published criticism over the quality of included studies.⁴ In exercise research, reviewers reported that ~2 g oral L-carnitine improved markers of muscle damage (creatine kinase, LDH, myoglobin) and soreness in some randomized trials, though results across studies were mixed.⁷ Conversely, Koeth et al. reported that microbiota-generated TMAO from L-carnitine was associated with adverse cardiovascular events in humans and accelerated atherosclerosis in mice, with omnivores producing more TMAO than vegans/vegetarians.⁵ These are reported research observations, not health claims.

Honest assessment

Strength of evidence

Grade B

Graded B. Mechanistic and animal data for L-carnitine’s role in fatty-acid oxidation are strong and well established,² and limited human RCT data exist (the cardiac meta-analysis⁴ and exercise-recovery trials⁷), but the human evidence is inconsistent: the secondary-prevention meta-analysis was contested for the quality of its source trials, and a separate line of research reported that L-carnitine’s microbiota metabolite TMAO is pro-atherogenic.⁵ The two findings have not been fully reconciled, so the net cardiovascular picture in humans remains unsettled. Pharmacokinetic half-life values vary by study and method: a single-oral-dose study reported a terminal half-life of ~60 h,³ whereas the levocarnitine prescribing label reports a terminal elimination half-life of ~17.4 h (IV, baseline-uncorrected).⁶

Handling

Reconstitution & storage

Reconstitute with bacteriostatic water for laboratory handling. Store lyophilised material frozen and reconstituted material refrigerated. Use Peptigo’s reconstitution calculator and storage cheat sheet for working figures.

References

PubChem Compound Summary, CID 10917 (L-Carnitine); CAS 541-15-1; InChIKey PHIQHXFUZVPYII-ZCFIWIBFSA-N. National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/compound/10917
Carnitine palmitoyltransferase / carnitine shuttle in mitochondrial fatty-acid oxidation (CPT1, carnitine-acylcarnitine translocase, CPT2); regulation by malonyl-CoA. ScienceDirect Topics / Carnitine palmitoyltransferase 1 (review). https://www.sciencedirect.com/topics/medicine-and-dentistry/carnitine-palmitoyltransferase-i
Cao Y, Wang YX, Liu CJ, Wang LX, Han ZW, Wang CB. Comparison of pharmacokinetics of L-carnitine, acetyl-L-carnitine and propionyl-L-carnitine after single oral administration of L-carnitine in healthy volunteers. Clin Invest Med. 2009;32(1):E13-9. PMID 19178874.
DiNicolantonio JJ, Lavie CJ, Fares H, Menezes AR, O’Keefe JH. L-carnitine in the secondary prevention of cardiovascular disease: systematic review and meta-analysis. Mayo Clin Proc. 2013;88(6):544-551. PMID 23597877.
Koeth RA, Wang Z, Levison BS, et al. Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med. 2013;19(5):576-585. PMID 23563705.
Levocarnitine (oral solution / tablets) prescribing information: absolute oral bioavailability ~15% (baseline-corrected), mean apparent terminal elimination half-life ~17.4 h (uncorrected for endogenous levocarnitine). DailyMed, National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ada35959-e317-4161-ae79-3475096c679f
Yarizadh H, Shab-Bidar S, Zamani B, Nazary Vanani A, Baharlooi H, Djafarian K. The Effect of L-Carnitine Supplementation on Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. J Am Coll Nutr. 2020;39(5):457-468. PMID 32154768.

Written by the Peptigo Research Team · scientifically reviewed by Peter, Peptigo Research Team · Last reviewed June 2026. We cite primary literature and flag where evidence is limited. Our sourcing & RUO policy →