L-carnitine is a compound made in the body from the amino acids lysine and methionine. It is also found in food, primarily in meat products, and therefore vegans and vegetarians might be low on it. For your body to produce it in sufficient amounts, you also need plenty of vitamin C.
L-carnitine can be converted to acetyl-L-carnitine, which crosses the blood-brain barrier more efficiently and is therefore studied for it’s neurophysiological effects such as improving the symptoms of depression and cognitive function.
Forms
L-Carnitine is also known as:
- Acetyl-L-Carnitine
- ALCAR
- Acetylcarnitine
- L-Carnitine-L-Tartrate
- GPLC
- Levocarnitine
It should not be confused with carnosine (a product of beta-alanine).
Mechanism
In tissues like muscle, L-carnitine is known to help “shuttle” longer chain fatty acids into the mitochondria which is the powerhouse of the cell where energy is produced. So it’s a transporter of fat and not a fat burner as it’s marketed commonly.
Benefits:
1. Peripheral artery disease: it can help reduce a symptom called intermittent claudication (leg pain during exercise) and improve exercise capacity.
2. Exercise: It may help reduce exercise-induced muscle soreness and muscle damage, particularly following resistance exercise.
3. Fertility: It may improve sperm quality in males with infertility. Similarly, it may improve ovulation and rate of pregnancy in women with polycystic ovary syndrome, however more studies are needed.
4. Liver Health: It can lower liver enzymes in people with nonalcoholic fatty liver disease (NAFLD).
5. Metabolic Health: It has minor beneficial effects on the metabolic syndrome, for example, reduction in blood pressure, blood glucose, body weight, blood lipids and markers of oxidative stress and chronic inflammation.
Evidence suggests that it may exert some of it’s potential beneficial effects by boosting antioxidant capacity, protecting cellular membranes from oxidative stress, and increasing nitric oxide levels.
Drawbacks
L-carnitine supplements may raise your blood levels of trimethylamine-N-oxide (TMAO) over time. High levels of TMAO are linked to an increased risk of heart disease.
Dosage
The standard dose for L-carnitine is between 500–2000 milligrams per day (mg/day).
Supplementation with up to 2000 mg/day of L-carnitine is considered safe for humans.
There are various other forms of carnitine supplementation available: The equivalent dosage is up to about 2700 mg/day for acetyl-L-carnitine and up to about 2900 mg/day for propionyl L-carnitine.
Bottomline:
Not all athletes may benefit from adding L-carnitine. Those with diseases like cirrhosis and kidney disease may benefit from a supplement. A qualified dietitian can identify if you are a candidate for supplementation and guide you with the dosing and duration of use.
~Shwetha Bhatia, Registered Dietitian (Indian Dietetic Association)