L-Carnitine
Also known as: Acetyl-L-Carnitine, ALCAR, L-Carnitine L-Tartrate, LCLT
The mitochondrial shuttle that transports fatty acids into cells for burning
Primary Benefit
Fat Transport and Oxidation
Standard Dose
1,000 to 2,000 mg/day
Evidence
Certifications
Overview
L-Carnitine is a naturally occurring amino acid derivative that plays an essential role in energy metabolism by transporting long-chain fatty acids across the inner mitochondrial membrane, where they are oxidized for fuel. While the body produces it endogenously, supplementation increases muscle carnitine content over time, potentially enhancing fat utilization during exercise.
Benefits & Evidence
- Transports fatty acids into mitochondria for energy production
- Reduces exercise-induced muscle damage and soreness
- May improve insulin sensitivity with long-term use
- Supports recovery through reduced oxidative stress
- Acetyl-L-Carnitine form also supports cognitive function
Clinical Study Summaries
Increasing skeletal muscle carnitine content in older individuals increases whole-body fat oxidation during moderate-intensity exercise
2011Aging Cell
Six months of L-carnitine supplementation with carbohydrate increased muscle carnitine by 20 percent and fat oxidation by 55 percent during exercise.
View studyL-carnitine supplementation in recovery after exercise
2018Nutrients
Carnitine supplementation significantly reduced markers of metabolic stress, muscle soreness, and damage following exercise compared to placebo.
View studyRecommended Dosage
| Standard Dose | 1,000 to 2,000 mg/day |
| Minimum | 500 mg/day |
| Maximum | 4,000 mg/day |
| Timing | With a carbohydrate-containing meal to maximize muscle uptake via insulin |
Side Effects & Interactions
Who Should Consider It
Good candidates
- Vegetarians and vegans with low dietary carnitine intake
- Older adults with age-related carnitine decline
- Those with type 2 diabetes or insulin resistance
- Athletes engaged in endurance training
Use caution or avoid
- Individuals with hypothyroidism without physician guidance
- People with trimethylaminuria (fish odor syndrome)