Alpha-lipoic acid is unique among biological antioxidants because it is soluble in both water and lipids. This allows it to neutralize free radicals just about everywhere in the body, inside and outside the cells.
Due to its unique sulfur containing structure, alpha-lipoic acid can scavenge several types of free radicals, such as the highly reactive hydroxyl, and singlet oxygen free radicals. It is also capable of suppressing the generation of free radicals in the first place, since alpha-lipoic acid chelates transition metals, such as iron and copper. Because alpha-lipoic acid is involved in so many different antioxidant functions in virtually all body tissues, it has been called the universal antioxidant. Besides being a universal free radical scavenger, alpha-lipoic acid can also recharge other antioxidant systems throughout the body. As mentioned earlier, it can extend the activity of vitamins C and E. In addition, alpha-lipoic acid can also regenerate glutathione.