What is it?
It is a naturally occurring compound produced in the body, and it assists in the conversion of glucose to energy. It also serves as an antioxidant.
The naturally occurring form of alpha-lipoic acid is called the R-isomer. Typically, synthetic products contain a 50/50 mixture of the R- and S- forms. Both the R-isomer-only and mixed forms are available as supplements.
What’s it used for?
There seems to not be extensive research done on Alpha-Lipoic Acid so far, but it appears to help increase insulin sensitivity in those with diabetes (type 2) if you are taking anywhere from 300mg to 1,200 mg per day.
Due to it being an antioxidant, it has found that it may be useful in combating things like radiation exposure or anything involving metal and chemical poisoning. It may also improve blood antioxidant status as well as a number of conditions such as liver ailments and age-related memory problems.
Sources: http://www.drweil.com/drw/u/ART03051/AlphaLipoic-Acid-ALA.html, Consumerlabs content summary for Alpha-Lipoic Acid Review