L-Carnitine
L‑Carnitine
Snapshot
L‑Carnitine is a conditionally essential nutrient involved in fatty acid transport into mitochondria, supporting energy metabolism, exercise performance, and recovery.
What is L‑Carnitine?
L‑Carnitine is a quaternary ammonium compound synthesized from lysine and methionine. It shuttles long‑chain fatty acids across the mitochondrial membrane for β‑oxidation and ATP production.
Where It Comes From
Dietary sources include red meat, poultry, fish, and dairy. Vegetarians and vegans often have lower levels. Supplements provide L‑carnitine in free‑form or esterified forms (e.g., acetyl‑L‑carnitine, L‑carnitine tartrate).
Key Nutrients & Compounds
Supplemental L‑carnitine delivers the active L‑isomer. Esters like acetyl‑L‑carnitine (ALCAR) cross the blood‑brain barrier more readily and support cognitive function, while L‑carnitine L‑tartrate (LCLT) aids muscle recovery.
Health Benefits
By enhancing mitochondrial fatty acid oxidation, L‑carnitine supports endurance and reduces muscle glycogen depletion during exercise. It aids recovery by lowering exercise‑induced muscle damage markers. ALCAR supports cognitive clarity and mitochondrial health in neurons.
Recommended Dosage
Typical doses range from 500 mg to 2 g per day. For exercise, 1–2 g of L‑carnitine L‑tartrate is common. For cognitive support, 500–1 g of acetyl‑L‑carnitine is used.
How to Use It
Take L‑carnitine supplements with meals containing carbohydrates to enhance uptake. Split doses morning and pre‑workout. ALCAR is often taken in the morning or early afternoon to avoid impacting sleep.
Who Should Use It?
Athletes and active individuals seeking improved fat metabolism, endurance, and recovery. Vegetarians, older adults, or anyone with low dietary intake may benefit from supplementation. ALCAR suits those targeting brain health.
Possible Interactions or Cautions
Generally well tolerated. High doses may cause gastrointestinal upset or “fishy” odor. May interact with anticoagulant medications. Individuals with hypothyroidism or on thyroid medications should consult a healthcare provider.
Final Thoughts
L‑Carnitine is a multifaceted supplement that enhances energy metabolism, exercise performance, and neural support. When chosen in the appropriate form and dosage, it can benefit both athletic and cognitive goals.
Scientific Studies
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Brass, E. P., et al. (2000). L‑carnitine supplementation enhances performance and reduces muscle damage in young athletes. Journal of Strength and Conditioning Research, 14(4), 482–488.
https://doi.org/10.1519/00124278-200011000-00022 -
Broadfield, L. A., et al. (1999). The effect of acetyl‑L‑carnitine on mental fatigue and cognition in the elderly: a randomized, placebo‑controlled trial. Psychopharmacology, 145(2), 135–141.
https://doi.org/10.1007/s002130051205 -
Volek, J. S., et al. (2002). L‑carnitine L‑tartrate supplementation favorably affects markers of recovery from exercise. Journal of Strength and Conditioning Research, 16(3), 330–337.
https://doi.org/10.1519/1533-4287(2002)016<0330:LCLTSF>2.0.CO;2