L-carnitine
L-carnitine (levocarnitine)
What is L-carnitine?
L-carnitine: Amino-acid-derived nutrient that transports long-chain fatty acids into mitochondria for beta-oxidation. The sources cited here most often discuss it for: Modest weight loss; Exercise recovery; Treats carnitine deficiency. Evidence label: Approved (specific use).
- Type
- Not a peptide
- Family
- Lipotropics & Nutrients
- Evidence label
- Approved (specific use) (5 of 5)
- Regulatory status
- FDA-approved as Carnitor (levocarnitine) for primary systemic carnitine deficiency and for inborn errors of metabolism that cause secondary carnitine deficiency.
- Goals discussed
- Fat Loss & Metabolism, Healing & Recovery, Muscle & Tone, Energy & Endurance
- Also called
- levocarnitine, CARNITOR, CARNITOR SF, acetyl-L-carnitine, ALC, L-carnitine L-tartrate, L-carnitine tartrate, L-C
- Last reviewed
- 2026-10-11
- Amino-acid-derived nutrient that transports long-chain fatty acids into mitochondria for beta-oxidation; FDA-approved as Carnitor (levocarnitine) for primary/secondary carnitine deficiency and dialysis-related deficiency; otherwise a supplement/injection.12
Not a peptide: an amino-acid-derived nutrient made in the body and found mainly in animal foods.
Regulatory status FDA-approved as Carnitor (levocarnitine) for primary systemic carnitine deficiency and for inborn errors of metabolism that cause secondary carnitine deficiency. 2
The potential harm of L-C in MetS and its association with pro-atherogenic metabolites raises concerns for its further use as a potential therapy and its widespread availability as a nutritional supplement.
Six-month placebo-controlled trial in 157 adults with metabolic syndrome and existing carotid plaque; plaque volume did not change but narrowing progressed more with carnitine.
What is L-carnitine researched for?
The three outcomes most discussed for L-carnitine in the sources below, as those sources report them. humanpeptides.fyi makes no claims of its own: a listed benefit can be unproven or can have failed in trials, and the label on each line says which.
What do researchers and users say about L-carnitine?
Compared to placebo, L-carnitine tartrate supplementation was able to improve perceived recovery and soreness (p = 0.021), and lower serum creatine kinase (p = 0.016).
Five-week placebo-controlled trial in 80 adults aged 21 to 65 ending in a high-volume exercise challenge.
Seizures have been reported to occur in patients with or without preexisting seizure activity receiving either oral or intravenous levocarnitine.
Adverse-reaction section of the US prescribing information for levocarnitine.
What side effects of L-carnitine are reported?
- TMAO elevation and possible atherosclerosis progression with chronic usehuman RCT9
- High-dose chronic oral use in dialysis can accumulate TMA/TMAOFDA label2
- Seizures, including more frequent or severe seizures in people with an existing seizure disorder.FDA label2
- Nausea, vomiting, abdominal cramps, diarrhea and a body odor.FDA label2
- Rash, hives and facial swelling.FDA label2
- May worsen symptoms of an underactive thyroid.secondary source (Dr. Axe)10
What do peptide guides say about L-carnitine?
- Dr. Axe Dr. Axe outlines several forms: acetyl-L-carnitine crosses into the brain, L-carnitine L-tartrate is used for exercise soreness, and D-carnitine is inactive and may even block the active form. 10
- Dr. Axe Because carnitine comes mainly from animal foods, Dr. Axe notes vegans and vegetarians face higher deficiency risk, and that diarrhea, dialysis, liver disorders and some medications can also deplete it. 10
- FDA label Its FDA-approved uses are primary systemic carnitine deficiency and inborn metabolic errors causing secondary deficiency, where supplementation sometimes rapidly relieved symptoms, particularly heart muscle disease. 2
What does the research say, system by system?
Body & tissues1
- Skeletal muscle (reduced exercise-induced damage markers)5
Hormones & physiology1
- Raises TMAO (gut-microbe metabolite linked to cardiovascular risk); 6-month RCT in metabolic syndrome showed increased carotid stenosis and LDL-Chuman RCT9
Cells & mitochondria1
- Shuttles long-chain fatty acids into mitochondria for beta-oxidationFDA label/biochemistry2
Weight & metabolism1
Muscle1
- Better preservation of strength/power after damaging exercisehuman RCT5
Also notable1
- Often added to lipotropic ('Lipo-C') injections, but at doses below those used in oral trials12
How strong is the evidence for L-carnitine?
FDA-approved for deficiency; many human RCTs showing small weight-loss and recovery effects
Approved by the FDA (or a major regulator) for at least one specific use. Approval covers that use only, not the other benefits listed. How tiers work
Questions about L-carnitine
What is L-carnitine?
Amino-acid-derived nutrient that transports long-chain fatty acids into mitochondria for beta-oxidation. Not a peptide: an amino-acid-derived nutrient made in the body and found mainly in animal foods.
Is L-carnitine FDA-approved?
FDA-approved as Carnitor (levocarnitine) for primary systemic carnitine deficiency and for inborn errors of metabolism that cause secondary carnitine deficiency.
What is L-carnitine researched for?
The sources cited on this page most often discuss three outcomes: Modest weight loss; Exercise recovery; Treats carnitine deficiency. Each line above shows what the source reports and how strong that evidence is.
What side effects of L-carnitine are reported?
Reported in the cited sources: TMAO elevation and possible atherosclerosis progression with chronic use; High-dose chronic oral use in dialysis can accumulate TMA/TMAO; Seizures, including more frequent or severe seizures in people with an existing seizure disorder. The list is not complete, and few listed risks does not mean a compound is safe.
How strong is the evidence for L-carnitine?
Evidence label: Approved (specific use). FDA-approved for deficiency; many human RCTs showing small weight-loss and recovery effects.
What else is L-carnitine called?
Names used for it include levocarnitine, CARNITOR, CARNITOR SF, acetyl-L-carnitine, ALC, L-carnitine L-tartrate, L-carnitine tartrate, L-C.
Does humanpeptides.fyi recommend L-carnitine?
No. humanpeptides.fyi makes no claims and no recommendations of its own. It summarizes and links to what others have published and posted. Nothing here is medical advice; talk to a licensed clinician.