A compound made from amino acids, found mainly in red meat.
Why it’s used: Carries fatty acids into the mitochondria so they can be burned for energy.
L-carnitine is a compound the body makes from the amino acids lysine and methionine, in the liver, kidneys and brain. It is also found in food. Red meat is the richest source, poultry, fish and dairy contain some, and vegetables, fruit and grains contain very little.
Carnitine carries fatty acids into the mitochondria, the parts of cells that use them to produce energy. Because the liver and kidneys make enough, healthy children and adults do not need to get carnitine from food or supplements. Researchers have studied carnitine in relation to exercise and other areas, but no health claims are authorised for it in the UK.
The two main forms in supplements are L-carnitine and acetyl-L-carnitine, with amounts listed in milligrams (mg). Some medicines can lower the body's carnitine levels, including some long-term antibiotics and anticonvulsants such as valproic acid and phenobarbital, which is one situation where a doctor might look at carnitine more closely.
3 findings behind this ingredient. Hover a card for the detail and the source.
Meta-analysis of 37 randomised controlled trials with 2,292 participants. L-carnitine lowered body weight by 1.21 kg, BMI by 0.24 kg/m² and fat mass by 2.08 kg, with the maximum effect at around 2,000 mg a day.
Meta-analysis of seven randomised controlled trials. L-carnitine improved muscle soreness at every time point up to 96 hours and reduced creatine kinase, myoglobin and lactate dehydrogenase at 24 hours.
Randomised, double-blind, placebo-controlled trial in 66 centenarians who tired after slight activity. Levocarnitine reduced fat mass, increased muscle mass, and improved fatigue severity and MMSE scores compared with placebo.
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L-carnitine carries fatty acids into the mitochondria so cells can use them for energy. The body makes its own from lysine and methionine, and red meat is the richest food source. Researchers have studied it in exercise, but it has no authorised health claims.
They are the two main forms of carnitine in supplements. Acetyl-L-carnitine is carnitine with an acetyl group attached. Both supply carnitine, so check the label for which form is used and how much of it each serving provides.
At 3g or more a day, carnitine supplements can cause nausea, vomiting, stomach cramps, diarrhoea and a fishy body odour, according to the NIH. High amounts can also increase seizure risk in people with seizure disorders, so check with your GP first.
Information only, not medical advice. If you take medication, are pregnant or breastfeeding, speak to your GP or pharmacist first.
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