Supplement
L-Carnitine
SaveAn amino acid derivative essential for transporting long-chain fatty acids into mitochondria for beta-oxidation. The body synthesizes sufficient amounts in healthy individuals, but levels decline with age.
Quick verdict
Good evidence for cardiovascular outcomes post-MI and in elderly with carnitine deficiency. Fat-burning claims for healthy young adults are largely unsupported.
Evidence score
A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.
What the research shows
A meta-analysis of 13 RCTs found L-carnitine reduced all-cause mortality by 27% in acute MI patients. Acetyl-L-carnitine shows benefit for diabetic neuropathy and cognitive decline in elderly. Fat-burning effects in healthy, carnitine-replete individuals are minimal. TMAO production from carnitine metabolism is a theoretical cardiovascular concern.
Benefits
- Facilitates mitochondrial fatty acid oxidation
- May reduce mortality post-myocardial infarction
- Acetyl-L-carnitine supports cognitive function in elderly
Dosage notes
L-carnitine: 1-3 g daily. Acetyl-L-carnitine: 500-2000 mg daily for cognitive effects. Take with carbohydrates to enhance muscle uptake.
Side effects
- Fishy body odor at high doses
- GI discomfort
- Nausea
- TMAO elevation (theoretical cardiovascular concern)
Who should be cautious
Gut bacteria convert carnitine to TMAO, which is associated with cardiovascular risk. This may offset benefits in some individuals, particularly red meat consumers.
What this page cannot tell you
Benefits are most pronounced in deficient populations (elderly, vegetarians, certain genetic conditions). Healthy omnivores may derive limited additional benefit.
Leaderboard scores
- Energy45
- Longevity45
- Recovery40
- Memory35
- Weight loss25
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