A sulphur-containing compound that functions as a coenzyme in the metabolism of carbohydrates and energy production. Alpha-lipoic acid participates in the oxidative decarboxylation of pyruvate and alpha-ketoglutarate, key steps linking glycolysis and the Krebs cycle. It also acts as a versatile antioxidant, working in both watery and fatty environments and helping to regenerate other antioxidants such as vitamins C and E. The body synthesises small amounts, and it occurs naturally in organ meats, spinach, and broccoli. Sold as a supplement, it is marketed for blood sugar control and nerve health in diabetes, though clinical evidence remains mixed and professional guidance is advisable.