Full profile
| Also known as | ALCAR, Acetyl-L-carnitine HCl, ALC |
|---|---|
| Best for | Cellular energy support · Age-related cognitive support · Mental fatigue on long days |
| Evidence grade | Grade C — Limited — early or small human trials |
| Studied dose range | 1.5–3 g daily in trials, usually split into two doses (Health Canada permits up to 4 g/day). |
| Time to effect | Cumulative over weeks to months; no reliable same-day effect. |
| Best form | Acetyl-L-carnitine HCl — the stable, water-soluble oral form used in research. |
| Food sources | Red meat (beef, lamb), Smaller amounts in pork, fish, poultry, dairy |
Evidence, honestly graded
The only Cochrane review of acetyl-L-carnitine and cognition is in a dementia population and found insufficient evidence to recommend it; there is no dedicated Cochrane review in healthy, unimpaired adults. Most positive human data is in older adults and mild cognitive impairment (1.5–3 g/day over 12–24 weeks), where effects are modest — so the grade is honest for a healthy-adult use case.
See the full grading rubric — study type, replication, population match, and dose adequacy — in The Evidence Standard.
Side effects
- Generally well tolerated
- GI discomfort (nausea, cramping)
- "Fishy" body odor at higher doses
- Restlessness or insomnia if taken late
Who should avoid it or check first
- Pregnant or breastfeeding without clinician guidance
- Seizure disorder without review
- Kidney disease without review
- Hypothyroidism without review
Interactions
- May interact with blood thinners (e.g. warfarin) and thyroid medication — discuss with a clinician
Stacks well with
- Citicoline
- Phosphatidylserine
- Rhodiola Rosea
What to look for on a label
- The acetylated form (ALCAR) is chosen because it reaches the brain better than plain L-carnitine.
- Works cumulatively over weeks — pair with consistent daily use rather than expecting an acute lift.
References
- Hudson & Tabet 2003, Cochrane Database Syst Rev. Cochrane review of acetyl-L-carnitine in dementia (no dedicated review exists in healthy, unimpaired adults). PMID 12804452; doi:10.1002/14651858.CD003158. Educational, not a product claim.
- Montgomery 2003, Int Clin Psychopharmacol — meta-analysis. Modest benefit in mild cognitive impairment and mild Alzheimer's at 1.5–3 g/day over 12–24 weeks. PMID 12598816. Educational.
Grades and studied doses are our conservative reading of the human research, shown for education. They are not product claims, and a studied dose is not a recommended dose.
See how Acetyl-L-Carnitine compares on grade, dose, and goal in the Evidence Explorer.
