L-Carnitine for Enhanced Athletic Performance
Carnitine does not act as a fat burner, but long-term supplementation with carbohydrate improves recovery and reduces muscle damage markers.
Overview
Verdict
How It Works
Dosing & Protocol
Typical dose
- Recommended dose
- 2-4 g/day L-carnitine L-tartrate taken with a carbohydrate-containing meal, for at least 12 weeks
- Expected timeframe
- 8-12 weeks
Protocol
- form
- L-carnitine L-tartrate is the form used in most exercise trials. Acetyl-L-carnitine is used for cognitive endpoints and propionyl-L-carnitine for vascular ones. Never use D-carnitine or DL-carnitine, which are harmful
- duration
- At least 12 weeks - muscle carnitine content changes only slowly
- co factor
- Take with a substantial carbohydrate-containing meal. This matters more than the dose: muscle carnitine uptake is insulin-dependent, and studies show that without a marked insulin response, oral carnitine simply raises plasma levels without increasing muscle content - which is likely why many earlier trials found nothing. Evidence is mixed. Trials of L-carnitine L-tartrate at 2 g/day report reduced markers of muscle damage and soreness and improved recovery after resistance exercise, which is the most consistent finding. Effects on strength, power, endurance performance and fat oxidation are inconsistent, and studies achieving genuine muscle carnitine loading over months are few.
- titration
- Up to 3-4 g/day in divided doses; do not exceed 4 g/day
- starting dose
- 2 g/day L-carnitine L-tartrate with a meal containing carbohydrate
Evidence
What the studies say
No studies are yet linked to both L-Carnitine and Enhanced Athletic Performance.
Safety
Caveats
Safety ceiling: doses above 3 g/day commonly cause nausea, vomiting, abdominal cramps, diarrhoea and a distinctive fishy body odour; keep below 4 g/day. The more substantive concern is TMAO - gut bacteria convert carnitine to trimethylamine, which the liver oxidises to trimethylamine-N-oxide, a metabolite associated in observational studies with increased cardiovascular risk, and carnitine supplementation demonstrably raises TMAO, particularly in omnivores. The clinical significance is debated and unresolved, but it is a reason for caution with long-term high-dose use, especially in anyone with existing cardiovascular disease. Carnitine may increase the effect of warfarin - monitor INR. Avoid in seizure disorders, where carnitine has been reported to increase seizure frequency, and in hypothyroidism, where it may interfere with thyroid hormone action. Use with caution in kidney disease, where carnitine accumulates. No established upper intake level for supplements, and insufficient safety data in pregnancy and breastfeeding - avoid in both.
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Medical Disclaimer
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Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.