Swanson Ultra R-Fraction Alpha Lipoic Acid features R isomer alpha-lipoic acid, the only form that occurs in the human body, and the one responsible for most of alpha-lipoic acid's beneficial effects. This product provides R-alpha-lipoic acid bound through a patented process, making it a highly stabilized form of R-alpha-lipoic acid capable of delivering the antioxidant nutrient faster than other forms.