Natural Factors R-Alpha-Lipoic Acid - 100 mg - Proven to stay in the body significantly longer than the regular 'S' form of Alpha-lipoic acid, and is involved in energy production. Alpha-lipoic acid works together with vitamin E and vitamin C to protect the entire cell from oxidative stress. As an antioxidant it is a very small molecule that is efficiently absorbed and easily crosses cell membranes. Alpha-lipoic acid is both fat- and water-soluble, so it can quench free radicals both inside and outside the cell. It also directly recycles vitamins C and glutathione and indirectly recycles vitamin E.