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evidence · mechanism · dose
Supplements/Amino Acid

L-Carnitine

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

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

Energy ProductionFat LossAthletic PerformanceBrain & Cognitive

Overview

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

Natural sources
  • Red meat
  • Dairy
Common forms
  • L-Carnitine tartrate
  • Acetyl-L-Carnitine (ALCAR)
  • Propionyl-L-Carnitine

Mechanism of action

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

Pathways
  • · Fatty acid β-oxidation

Effects on the body

Supports
Fatty acid oxidation
Decreases
Exercise-induced damage

Organ system effects

Cardiovascular

Improves outcomes post-MI.

Brain & CNS

ALCAR studied for cognitive aging.

Evidence-based benefits

Reduces post-MI mortality

Moderate evidence

Improves cognitive scores in mild AD

Moderate evidence

Reduces exercise-induced muscle damage

Moderate evidence

Potential side effects

Common
  • · Fishy odor at high doses
Rare
    Serious
    • · Possible TMAO elevation

    Drug interactions

    Warfarin
    May potentiate.
    moderate
    Levothyroxine
    Mild thyroid antagonism.
    minor

    Supplement interactions

    Pairs well with

    None listed.

    Avoid combining with

    No specific avoidances listed.

    Dosing & bioavailability

    Typical dose
    1–2 g L-carnitine or 500–1500 mg ALCAR

    Where to buy

    Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

    Amino Acid
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    Amazon
    Wide selection · fast shipping
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    iHerb
    Global delivery · curated brands
    Amino Acid
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    Thorne
    Practitioner-grade · NSF tested

    Scientific evidence (10)

    Systematic reviewExamine.com Supplement Database · 2023

    L-Carnitine: pharmacology, clinical evidence, and safety — narrative review

    Examine.com Research Team

    Curated narrative review of human and preclinical evidence for L-Carnitine, including mechanism, typical dosing, and safety considerations.

    Key findings

    Best-supported outcome: Reduces post-MI mortality (evidence: moderate). Additional outcomes and limitations summarized in the full profile.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: L-Carnitine — Reduces post-MI mortality

    Live PubMed search

    Live results for "L-Carnitine Reduces post-MI mortality" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    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.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: L-Carnitine — Improves cognitive scores in mild AD

    Live PubMed search

    Live results for "L-Carnitine Improves cognitive scores in mild AD" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    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.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: L-Carnitine — Reduces exercise-induced muscle damage

    Live PubMed search

    Live results for "L-Carnitine Reduces exercise-induced muscle damage" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    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.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: L-Carnitine — randomized controlled trial

    Live PubMed search

    Live results for "L-Carnitine randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching L-Carnitine and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: L-Carnitine — meta-analysis

    Live PubMed search

    Live results for "L-Carnitine meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

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

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: L-Carnitine — pharmacokinetics

    Live PubMed search

    Live results for "L-Carnitine pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

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

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: L-Carnitine — safety adverse events

    Live PubMed search

    Live results for "L-Carnitine safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching L-Carnitine and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: L-Carnitine — dose response

    Live PubMed search

    Live results for "L-Carnitine dose response" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

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

    Open study
    Systematic reviewGoogle Scholar · 1970

    Google Scholar: L-Carnitine — clinical evidence

    Live Scholar search

    Cross-database citation index for L-Carnitine as it relates to "clinical evidence".

    Key findings

    Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

    Open study
    Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.