L-Carnitine (Tartrate)
Commonly used for
Athletic Performance
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What is it? / Overview
Carnitine shuttles fatty acids into mitochondria for energy and buffers acetyl groups during intense exercise; a meta-analysis of 7 RCTs found LCLT supplementation reduced markers of exercise-induced muscle damage (creatine kinase, myoglobin) and soreness after exertion, though the effect on direct performance is inconsistent. Long-term high-dose use also raises TMAO, a marker with a theoretical cardiovascular-risk association worth being aware of.
How is it used? / Administration
Form: L-carnitine L-tartrate (LCLT) -- the exercise-recovery form, distinct from the existing Acetyl-L-Carnitine (ALCAR) entry, which is more cognition-oriented
Typical dose studied: ~2 g/day (as LCLT)
Timing: With a carbohydrate-containing meal -- insulin drives muscle carnitine uptake; carnitine alone is poorly retained
Distinct from the existing Acetyl-L-Carnitine (ALCAR) entry (see that separate entry) -- ALCAR is more CNS/cognition-oriented at a different dose, while LCLT is specifically the exercise-recovery form and requires carbohydrate co-ingestion for meaningful uptake.
How well does it work? / Evidence
~ Moderate evidence
Who should avoid it?
Avoid with: Epilepsy / Seizure disorder; Hypothyroidism / Hashimoto's thyroiditis; Chronic kidney disease (Stage 3, 4, or 5) — NOT on dialysis; Dialysis (Hemodialysis or Peritoneal Dialysis)
Interacts with: Warfarin -- reports of enhanced anticoagulation; Thyroid hormone replacement -- carnitine can theoretically blunt thyroid hormone action
Already taking it? Reasonable to continue if paired with a carbohydrate-containing meal, which the evidence shows is essential for actual muscle uptake -- taken alone or without carbs, retention is poor. Recovery benefit (less soreness, lower muscle-damage markers) is more consistently supported than a direct performance boost.
Research & references
Yarizadh H et al. (2020). The Effect of L-Carnitine Supplementation on Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis. Journal of the American College of Nutrition. Ho JY et al. (2010). L-Carnitine L-Tartrate Supplementation Favorably Affects Biochemical Markers of Recovery From Physical Exertion. Metabolism. Wall BT et al. (2011). Chronic Oral Ingestion of L-Carnitine and Carbohydrate Increases Muscle Carnitine Content and Alters Muscle Fuel Metabolism During Exercise in Humans. The Journal of Physiology.
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