Discovered in 1951, lipoic acid (also called alpha-lipoic acid or ALA) has long been recognized as a coenzyme that helps break down sugar for energy production during the Krebs cycle. Only recently has its therapeutic potential been realized.
Lipoic acid is medically approved in Germany for treating adult-onset type II diabetes and its complications. Ironically, the research that demonstrated its increased blood sugar utilization was done in the United States. Lipoic acid is not a controlling factor in such instances, but research shows that a high intake (300 to 600mg per day) tends to normalize blood sugar levels in diabetics. glucose utilization by thioctic acid,” Biophys Acta 222: 583-86, 1970]
Lipoic acid also fights free radical damage in both fatty and watery regions of cells and helps to recycle other antioxidants in what is described as “antioxidant synergism”. A recent study showed that when lipoic acid was missing, other antioxidants did not interact well, thereby reducing their ability to protect cells.
It can be found in potatoes, carrots, broccoli, yeast, beets, yams and kohlrabi, and is also abundant in red meat. It is a vitamin-like antioxidant that is also produced naturally in the body; it is the only antioxidant that is fat- and water-soluble; it is easily absorbed and transported across cell membranes. Whereas many antioxidants only provide protection outside of cells, ALA is broken down inside cells to dihydrolipoic acid – an even more potent antioxidant. It also regenerates other antioxidants like vitamin C, vitamin E and glutathione.
It protects the liver from alcohol damage, the lungs from smoke damage, and enhances glucose disposal in type II diabetes and reduces associated neuropathy and cataracts. Individuals with capillary fragility (bruise easily) can benefit. While some human studies involve doses as high as 1,000mg daily, 100mg is sufficient to obtain the antioxidant effects in most cases.
Clinical applications for this nutrient include the following conditions: diabetic polyneuropathy, cataracts, glaucoma, ischemia-reperfusion injury, radiation injury, metal toxicity, Amanita mushroom poisoning and CCl4 poisoning. Because of its unique characteristics ALA is likely to have therapeutic application in a wide range of additional clinical conditions.
No RDA has been established. Humans are usually not deficient in alpha-lipoic acid, but supplementation can help in some conditions.