Carnitine is a naturally occurring amino acid derivative that’s often taken as a supplement. It plays a crucial role in the production of energy by transporting fatty acids into your cells’ mitochondria. The mitochondria act as engines within your cells, burning these fats to create usable energy.  About 98% of your stores are contained in your muscles, along with trace amounts in your liver and blood Your body can produce L-carnitine out of the amino acids lysine and methionine.  For your body to produce it in sufficient amounts, you also need plenty of vitamin C. In addition to the L-carnitine produced in your body, you can also obtain small amounts by eating animal products like meat or fish. Vegans or people with certain genetic issues may be unable to produce or obtain enough. This makes L-carnitine a conditionally essential nutrient.