Supplement Scholar
Amino Acid

L-Carnitine

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L-Carnitine. Shuttles long-chain fatty acids into mitochondria for β-oxidation.

How it works. Carries long-chain acyl groups across mitochondrial membrane via CPT-I/II shuttle.

What the research supports. 3 graded claims. Strongest: Reduces post-MI mortality (moderate).

How much to take. Typical dose: 1–2 g L-carnitine or 500–1500 mg ALCAR.

Side effects and interactions. 2 medication interactions listed. Serious: Possible TMAO elevation.

Stacking. Pairs well with Omega-3 (EPA/DHA), Alpha-GPC or CDP-choline.

Common forms. Available as L-Carnitine tartrate, Acetyl-L-Carnitine (ALCAR), Propionyl-L-Carnitine.

Key studies. 10 studies cited. The strongest are listed with links to PubMed.

Community. Experiences from people who have tried L-Carnitine. Anecdotes are not medical advice.

L-Carnitine. Shuttles long-chain fatty acids into mitochondria for β-oxidation.

Molecular structureC7H15NO3 · 161.20 g/mol

What it is

Shuttles long-chain fatty acids into mitochondria for β-oxidation.

Also called

Acetyl-L-Carnitine (ALCAR)L-Carnitine Tartrate

Food sources

Red meatDairy

Goals

Energy ProductionFat LossAthletic PerformanceBrain & Cognitive

How it works

Carries long-chain acyl groups across mitochondrial membrane via CPT-I/II shuttle.

Pathways

  • Fatty acid β-oxidation

Effects

  • +Fatty acid oxidation supports
  • ↓Exercise-induced damage decreases

What the research supports

Reduces post-MI mortalitymoderate
Improves cognitive scores in mild ADmoderate
Reduces exercise-induced muscle damagemoderate

Strong: consistent results across large trials or meta-analyses. Moderate: several trials, mostly positive. Limited: small or mixed studies. Preclinical: animal or cell research only.

Typical dose
1–2 g L-carnitine or 500–1500 mg ALCAR
TimingConsistent daily timing recommended; split larger doses if GI tolerance is a concern.
With foodEither with or without food.
Best formMost evidence is based on the l-carnitine tartrate form.
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Side effects & interactions

Common side effects

  • Fishy odor at high doses

Serious

  • Possible TMAO elevation

Medication interactions

Warfarinmoderate

May potentiate.

Levothyroxineminor

Mild thyroid antagonism.

Check any supplement–medication combination with your pharmacist before starting.

Combines with

Pairs well

  • Omega-3 (EPA/DHA)Membrane fluidity and neuronal signaling support.
  • Alpha-GPC or CDP-cholineProvides choline substrate for acetylcholine synthesis.

Common forms

  • L-Carnitine tartrate
  • Acetyl-L-Carnitine (ALCAR)
  • Propionyl-L-Carnitine

Key studies

10 studies cited in total.

PubMed: L-Carnitine — Reduces post-MI mortality ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching L-Carnitine and "Reduces post-MI mortality". Filter by RCT, meta-analysis, or year on the results page.

PubMed: L-Carnitine — Improves cognitive scores in mild AD ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching L-Carnitine and "Improves cognitive scores in mild AD". Filter by RCT, meta-analysis, or year on the results page.

PubMed: L-Carnitine — Reduces exercise-induced muscle damage ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching L-Carnitine and "Reduces exercise-induced muscle damage". Filter by RCT, meta-analysis, or year on the results page.

Discussion

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