L-Carnitine
L-carnitine is a compound the body makes from the amino acids lysine and methionine and also gets from meat. It carries fatty acids into the mitochondria to be burned for energy.
Also listed as Acetyl-L-Carnitine, ALCAR, Acetylcarnitine, L-Carnitine-L-Tartrate
How much weight changed in trials?
A 2020 meta-analysis pooled 37 randomized trials with 2,292 participants. L-carnitine groups lost an average of 1.21 kg more than controls, with a 95% confidence interval from 0.68 to 1.73 kg. Waist circumference and body-fat percentage did not significantly change. The authors described a modest effect, particularly in overweight or obese adults; restricting the analysis to high-quality trials confirmed only the body-weight finding. 1
The pooled weight difference was modest, and other measures of body composition did not consistently improve. 1
Could it make the next workout less sore?
A review of seven trials found less muscle soreness after exercise. Several blood markers of muscle damage improved at 24 hours, but not at later measurements. Benefits for muscle damage were concentrated in resistance-training groups and untrained participants. This is an interesting recovery signal, although soreness and blood markers do not directly measure better sporting performance. 2
Small trial pools suggest less soreness, with narrower and shorter-lived changes in muscle-damage markers. 2
Why study acetyl-L-carnitine for memory?
Researchers have proposed that acetyl-L-carnitine could support acetylcholine, a chemical involved in memory, and mitochondrial function in Alzheimer’s disease. NIH describes conflicting reviews: some short-term test scores improved, but a Cochrane review found no improvement in functional ability or overall dementia severity. These older studies in people with cognitive impairment do not establish better focus in healthy adults. 3
Effects by health goal
Open an effect to see the studies behind its rating. Bars show the size of the effect; the letter grades the evidence.
Longevity1 effect
Immune Support1 effect
Cognition4 effects
Energy2 effects
Fitness2 effects
Weight Management2 effects
Cardiovascular1 effect
All studies
29 publications are linked to L-Carnitine, newest first.
Sources
- The Effect of L-Carnitine Supplementation on Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Randomized Clinical Trials Journal of the American College of Nutrition, 2020 · Study record
- Carnitine: Fact Sheet for Health Professionals NIH Office of Dietary Supplements