In addition to functioning as an antioxidant, this hard-working nutrient assists the B vitamins in producing energy from the proteins, carbohydrates, and fats consumed through foods.
Intravenous forms of alpha-lipoic acid are administered in hospitals to treat cases of acute mushroom poisoning and for other cases of acute poisoning that affect the liver.
Studies indicate that alpha-lipoic acid supplements hold promise for treating various disorders, including HIV infection, liver ailments, and glaucoma. But it has been most intensively studied for preventing complications from diabetes.
Specifically, alpha-lipoic acid may help to:
· Treat symptoms of nerve damage in people with diabetes. Alpha-lipoic acid has been used for decades in Europe to counter nerve damage in people with diabetes (types 1 and 2). Known as diabetic neuropathy, this often very painful condition tends to develop in people who have had uncontrolled diabetes for a long time. The neuropathy may be caused in part by free-radical damage to nerves resulting from poorly regulated blood sugar (glucose). As an antioxidant, alpha-lipoic acid helps to block such damage. In addition, because of its effect on glucose metabolism, lipoic acid my improve the glucose-lowering action of insulin (the hormone that regulates blood sugar).
In one clinical trial, 328 people with diabetic neuropathy received either 100 mg, 600 mg, or 1,200 mg a day of alpha-lipoic acid for three weeks. Participants who took 600 mg daily had the greatest reduction in pain and numbness. And in a separate study, blood sugar levels dropped in 74 people with type 2 diabetes who took 600 mg or more of alpha-lipoic acid daily.
Alpha-lipoic acid may also aid the large percentage (approximately 25%) of people with diabetes who risk sudden death from nerve-related heart damage. In one study, improved heart function was observed in people at risk for this complication who took 800 mg of alpha-lipoic acid daily for four months.
· Preserve brain function in aging adults. Results from animal studies indicate that alpha-lipoic acid may improve long-term memory. Much remains to be learned about whether this occurs in humans, but it may be worth trying this powerful antioxidant when a disease such as Alzheimer's starts to erode memory. In addition, alpha-lipoic acid holds promise for preserving brain cells following a stroke or other type of trauma that restricts blood flow to the brain.
· Prevent cancer. As an antioxidant, alpha-lipoic acid holds promise for protecting the body against changes in healthy cells that lead to cancer. The evidence for this cancer-preventive effect is still preliminary, however.
· Lessen numbness and tingling. Alpha-lipoic acid may benefit anyone whose limbs tend to tingle or become numb, or "fall asleep" due to nerve compression. In animal studies, alpha-lipoic acid increased blood flow to the nerves and improved transmission of nerve impulses.
· Protect the liver in cases of hepatitis and other types of liver disease. As an antioxidant, alpha-lipoic acid shields the liver from potentially harmful cell changes and assists it in flushing toxins from the body. This makes it useful in treating such liver disorders as chronic hepatitis and cirrhosis. Alpha-lipoic acid supplements have also proved effective in minimizing liver toxicity following exposure to poisons such as heavy metals (including lead) and toxic industrial chemicals such as carbon tetrachloride.
· Combat chronic fatigue syndrome. Because it plays a part in cellular energy production, some nutritionally oriented physicians recommend alpha-lipoic acid for the treatment of chronic fatigue syndrome. While evidence of its effectiveness for this condition is anecdotal, alpha-lipoic acid is a broad-spectrum antioxidant and immune system booster. This means it may be able to play a valuable role in increasing energy and maintaining overall health in chronic fatigue syndrome sufferers.
· Reduce the incidence of cataracts. Alpha-lipoic acid has kept cataracts from forming in animals, an effect that may occur in humans, too, but still requires more investigation. The compound also increases the potency of vitamins C and E, both nutrients that protect the eye's lens from harmful ultraviolet light.
Lipoic acid, also known as alpha-lipoic acid, is a sulfur-containing fatty acid. It is found inside every cell of the body, where it helps generate the energy that keeps us alive and functioning. Lipoic acid is a key part of the metabolic machinery that turns glucose (blood sugar) into energy for the body's needs.
Lipoic acid is an antioxidant, which means that it neutralizes naturally occurring, but harmful, chemicals known as free radicals. Unlike other antioxidants, which work only in water or fatty tissues, lipoic acid is unusual in that it functions in both water and fat.1,2 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.
Antioxidants are a bit like kamikaze pilots, sacrificing themselves to knock out free radicals. One of the more interesting findings about lipoic acid is that it may help regenerate other antioxidants that have been used up. In addition, lipoic acid may be able to do the work of other antioxidants when the body is deficient in them.3,4
It is thought that certain nerve diseases are at least partially caused 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. This is the rationale for studies on the potential benefits of lipoic acid for diabetic neuropathy.
A healthy body makes enough lipoic acid to supply its requirements; external sources are not necessary. However, several medical conditions appear to be accompanied by low levels of lipoic acid5—specifically, diabetes, liver cirrhosis, and atherosclerosis—which suggests (but definitely does not prove) that supplementation would 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 – 200 mg three times daily. In studies that found benefits, several weeks of treatment were often 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 for decades in Germany to treat diabetic peripheral neuropathy. This is a condition caused by diabetes in which nerves leading to the arms and legs become damaged, leading to numbness, pain, and other symptoms. Free radicals are hypothesized to play a role in neuropathy, and on this basis lipoic acid has been tried as a treatment. However, the evidence for benefit is largely limited to studies that used the intravenous form of this supplement.6,7,8
Another set of nerves may become damaged in diabetes as well: the “autonomic nerves” that control internal organs. When this occurs in the heart ("cardiac autonomic neuropathy") it leads to irregularities of heart rhythm. There is some evidence that lipoic acid supplements may be helpful for this condition.9
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 disease of the heart, kidneys and small blood vessels.10–14,28,29
In addition, lipoic acid may be helpful for burning mouth syndrome (BMS), a condition characterized by unexplained scalding sensations in the mouth.30
One animal study suggests that lipoic acid might help prevent age-related hearing loss.15 Similarly weak evidence hints that lipoic acid might be helpful for glaucoma.31Other uses for which lipoic acid has been proposed include preventing cancer and heart disease, and treating or preventing cataracts.
There is some evidence that 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 and contradictory.
A double-blind, placebo-controlled study of 500 people with diabetic neuropathy found that intravenous lipoic acid helped reduce symptoms over a 3-week period; however, long-term oral supplementation did not prove effective.16
A previous double-blind, placebo-controlled study also found benefit with intravenous lipoic acid.17,18
A few studies found oral lipoic acid effective; however, they were too small or too poorly designed to mean much.19–23
There is some preliminary evidence that lipoic acid may be more effective if it is combined with GLA (gamma-linolenic acid), another supplement used for diabetic peripheral neuropathy.24,25
There is better evidence for oral lipoic acid in a form of diabetic neuropathy affecting the nerves that supply the heart: autonomic neuropathy.
Not only does diabetes damage the nerves in the arms and legs, but it can also affect deep nerves that control organs such as the heart and digestive tract. The DEKAN (Deutsche Kardiale Autonome Neuropathie) study followed 73 people with diabetes who had symptoms caused by nerve damage affecting the heart. Treatment with 800 mg daily of oral lipoic acid showed statistically significant improvement compared to placebo and caused no significant side effects.26
Individuals with BMS feel chronic scalding pain in the mouth, as if they had consumed an excessively hot drink. Although the cause of BMS is not known, the symptoms resemble those of neuropathy, and for that reason researchers have investigated the potential benefits of lipoic acid.
In a two-month, double-blind trial involving 60 people with BMS, use of lipoic acid significantly reduced symptoms as compared to placebo.