It is important to note that the only naturally occurring, and consequently most effective, forms of alpha lipoic acid are the R-lipoic acid and R-dihydrolipoic acid forms. These are the types naturally found in plants, animals, and the human body and due to their chirally correct nature (being in the R isomer form) are responsible for the specific beneficial effects of alpha lipoic acid. It is important that these forms be distinguished from S-lipoic acid, which is not found in nature and is merely a by-product of chemical synthesis when companies artificially create less expensive alpha lipoic acid products. Most commercial products that are called “alpha lipoic acid” are actually a 50/50 mixture of S-lipoic acid and R-lipoic acid (this combination is known as “racemic alpha lipoic acid”). It’s important that the label specifically states that the R-lipoic acid form is used, as it is the only type that functions as a cofactor for mitochondrial enzymes and is also ten times more effective than racemic alpha lipoic acid as an antioxidant.