Lipoic acid, also known as alpha-lipoic acid, is a sulfur-containing fatty acid found inside every cell of the body. It helps generate the energy which maintains life. Lipoic acid is a key part of the metabolic machinery that turns glucose (blood sugar) into energy. Lipoic acid is an antioxidant, which means that it neutralizes free radicals which result from the necessary oxidative processes in the body. Unlike other antioxidants which work only in water or fatty tissues, lipoic acid functions in both water and fat. By comparison, vitamin E works only in fat and vitamin C works only in water. This gives lipoic acid an unusually broad spectrum of antioxidant action. Lipoic helps regenerate other antioxidants that have been used up (oxidized). Lipoic acid may be able to do the work of other antioxidants when the body is deficient in them. It is thought that certain nerve diseases are caused at least partially by free radical damage. Thanks to its combined fat and water solubility, lipoic acid can get into all the parts of a nerve cell and potentially protect it against such damage. At least this is the rationale for studies on the potential benefits of lipoic acid for diabetic neuropathy. Also, IV lipoic acid has been found to be very helpful in slowing, and in some cases arresting the growth of various cancers.
A healthy body makes enough lipoic acid to supply its requirements and external sources are not necessary. However, several medical conditions appear to be accompanied by low levels of lipoic acid — specifically atherosclerosis, diabetes , and liver cirrhosis — which suggests that supplementation may be helpful. Liver and yeast contain some lipoic acid. Nonetheless, supplements are necessary to obtain therapeutic dosages.
The typical dosage of oral lipoic acid for treating complications of diabetes is 100 to 200 mg three times daily. In studies that found benefits, several weeks of treatment were usually necessary for full effects to develop. For use as a general antioxidant, a lower dosage of 20 to 50 mg daily is commonly recommended, although there is no evidence that taking lipoic acid in this way offers any health benefit.
Lipoic acid has been widely used in Germany for many years to treat diabetic peripheral neuropathy, a condition caused by diabetes in which nerves leading to the arms and legs become damaged, resulting in numbness, pain, and other symptoms. Intravenous lipoic acid can reduce symptoms of diabetic peripheral neuropathy, at least in the short-term, however, the evidence for oral lipoic acid remains weak. Free radicals are hypothesized to play a role in peripheral neuropathy, and on this basis lipoic acid has been used as a treatment. However, the evidence for benefit is largely limited to studies that used the intravenous form of this supplement. The typical intravenous dose is 600 mg. given over 30-45 minutes several times per week. The “autonomic nerves” that control internal organs may become damaged in diabetes as well. When this occurs in the heart it is called “cardiac autonomic neuropathy” and it leads to irregularities of heart rhythm. There is some evidence that lipoic acid supplements may be helpful for this condition at a dose of 800 mg. orally and of course intravenous administration should be even more potent. Preliminary and sometimes contradictory evidence suggests that lipoic acid may improve other aspects of diabetes, including blood sugar control and the development of long-term complications such as diseases of the heart, kidneys, and small blood vessels. Lipoic acid may be helpful for burning mouth syndrome (BMS) , a condition characterized by unexplained scalding sensations in the mouth. There is some evidence for the use of lipoic acid to help prevent migraine headaches. A cream containing 5% lipoic acid helps repair sun-damaged skin. One animal study suggests that lipoic acid might help prevent age-related hearing loss. Similarly weak evidence hints that lipoic acid might be helpful for glaucoma, as well as for reducing the side effects (specifically, cardiac toxicity) of the some cancer chemotherapy agents. Lipoic acid has been proposed as an aid in preventing cancer and heart disease , and treating or preventing cataracts. Lipoic acid appears to have no significant side effects at dosages up to 1,800 mg daily. Safety for young children, women who are pregnant or nursing, or those with severe liver or kidney disease has not been established.