L-carnitine is a vitamin-like nutrient that can be produced in the body from the amino acids methionine and lysine. The body's cells depend on L-carnitine to burn fat. The nutrient is responsible for transporting fatty acids into the mitochondria. Thus, L-carnitine plays an important role in fat metabolism. Meat and dairy products have an above-average carnitine content. In addition, athletes in particular add L-carnitine to their bodies in the form of supplements to promote fat burning. They hope to gain two advantages from this: on the one hand, weight reduction and, on the other hand, improvement in endurance. If the body is given too much L-carnitine, this can lead to nausea, vomiting and diarrhoea.