L-carnitine is the standard biologically active form of carnitine, which is found in your body, foods and most supplements.

L-carnitine’s main role in your body involves mitochondrial function and energy production. In cells, it helps transport fatty acids into the mitochondria, where they can be burned for energy.

About 98% of your L-carnitine stores are contained in your muscles, along with trace amounts in your liver and blood.