What is the difference between L-carnitine and D-carnitine?

The main differences between L-carnitine and D-carnitine are reflected in their biological activities and effects on human health. 1. Biological activity: L-carnitine, also known as L- carnitine or vitamin BT, is a type of amino acid derivative that helps convert fat into energy and is nontoxic and without adverse effects on the human body. It has important physiological functions in the human body, including promoting fat metabolism, increasing energy levels, and protecting myocardial tissue. In contrast, D-carnitine is the chiral isomer of L-carnitine and has been proven harmful to humans, potentially causing muscle pain and, in severe cases, muscle atrophy. Moreover, it can inhibit the function of L-carnitine. 2. Chemical structure: Although L-carnitine and D-carnitine share the same molecular formula and chemical structure, their spatial configurations differ, resulting in distinctly different biological activities. This difference in spatial configuration leads to completely different roles of the two substances within the body. L-carnitine is beneficial to human health, whereas D-carnitine is harmful. When selecting and using related products, it is essential to clearly distinguish between L-carnitine and D-carnitine to ensure safety and efficacy.