How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
L-carnitine
A compound that transports fatty acids to the mitochondria to be burned — popular for weight loss, also studied for recovery.
Benefits
- Lowers oxidized LDL cholesterol in type 2 diabetics: −15.1 U/L versus −3.0 with placebo, at 2 g per day for 3 months (81 patients)
- Reduces inflammation markers (CRP) in coronary patients, at 1,000 mg per day for 12 weeks
- Mitigates muscle damage and soreness after exercise, according to a review of recovery studies
Precautions
Can cause digestive upset and body odor at high doses. Caution in case of renal insufficiency. It increases blood TMAO, a potentially pro-atherogenic compound whose long-term cardiovascular effect remains to be studied. At 2 g per day, it did not improve cancer-related fatigue compared to placebo.
Recommended dosage
1 to 2 g per day most often, for at least 12 weeks; taken with carbohydrates, it increases muscle carnitine.
How to take it
- Trial doses: 1 to 4 g per day, most often 1 to 2 g.
- With carbohydrates: taken with carbohydrates, L-carnitine can increase muscle carnitine, according to the review of prolonged intakes in healthy individuals.
- How long: this review only includes intakes of at least 12 weeks; this is also the duration of most trials in patients.
- A point to watch: prolonged intake increases TMAO, a compound that could promote atherosclerosis. Its long-term effects on the heart remain to be studied.
Did you know?
A controlled study has shown that 2 g/day of L-carnitine does not alleviate fatigue in cancer patients, even in cases of initial deficiency.
What the studies say
This systematic review evaluates the effects of prolonged L-carnitine supplementation (1 g to 4 g/day for at least 12 weeks) in healthy human subjects. It reports that L-carnitine, combined with carbohydrates, can increase total carnitine content in muscles. In centenarians, it was associated with an increase in muscle mass, an improvement in physical exercise tolerance, and cognitive function. However, it also led to an increase in plasma TMAO levels, a potentially pro-atherogenic compound, suggesting the need for further studies on its long-term cardiovascular effects.
Sawicka AK, Renzi G, Olek RA. — Journal of the International Society of Sports Nutrition (2020) — View the source study
Pairs well with
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more