L-Carnitine / Acetyl-L-Carnitine (ALCAR)

L-Carnitine is a fatty acid transporter essential for mitochondrial energy production; its acetylated form ALCAR additionally crosses the blood-brain barrier, acting as an acetylcholine precursor with evidence supporting cognitive function in aging and cardiovascular-metabolic risk reduction.

cognitivemetaboliclongevitycardiovascularmitochondrial

Dosing model

FLATFixed dose (no body-weight scaling).

Min dose

500 mg

Max dose

2000 mg

Rounding

100 mg

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Evidence

3 records

Depressive symptoms

Adults with depressive disorders, including older adults • systematic review and meta-analysis of RCTs

Moderate

Systematic review and meta-analysis found ALCAR significantly reduced depressive symptoms versus placebo or active comparators, with particularly pronounced effects in older adults; effect comparable to antidepressants but with a superior tolerability profile.

Dose: 2000 mg • Duration: 8–24 weeks

Citation: Veronese N, Stubbs B, Solmi M, et al. Acetyl-L-Carnitine Supplementation and the Treatment of Depressive Symptoms: A Systematic Review and Meta-Analysis. Psychosom Med. 2018;80(2):154-159.

Cognitive function in mild cognitive impairment and Alzheimer's disease

Adults with mild cognitive impairment or mild Alzheimer's disease • meta-analysis of RCTs

Moderate

Meta-analysis of 21 RCTs (n=1,204 evaluable) found a significant advantage for ALCAR versus placebo on both clinical scales and psychometric tests (ES=0.201, 95% CI 0.107–0.295 for integrated summary effect), with benefits emerging at 3 months and increasing over time at doses of 1.5–3.0 g/day.

Dose: 2000 mg • Duration: 3–12 months

Citation: Montgomery SA, Thal LJ, Amrein R. Meta-analysis of double blind randomized controlled clinical trials of acetyl-L-carnitine versus placebo in the treatment of mild cognitive impairment and mild Alzheimer's disease. Int Clin Psychopharmacol. 2003;18(2):61-71.

Metabolic syndrome biomarkers (waist circumference, blood pressure, lipids, glycemia)

Adults with metabolic syndrome or cardiovascular risk factors • systematic review and meta-analysis of RCTs

Moderate

Meta-analysis of 9 RCTs found L-carnitine (0.75–3 g/day, 8–24 weeks) significantly reduced waist circumference and systolic blood pressure; at doses >1 g/day, fasting blood sugar, triglycerides, and HDL-cholesterol were also significantly improved.

Dose: 1500 mg • Duration: 8–24 weeks

Citation: Choi M, Park S, Lee M. L-Carnitine's Effect on the Biomarkers of Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients. 2020;12(9):2795.

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