What Is It?

In the late 1980s, scientists realized that alpha-lipoic acid, a compound initially classified as a vitamin when it was discovered three decades earlier, possessed potent antioxidant properties that could prevent healthy cells from getting damaged by unstable oxygen molecules called free radicals. In fact, this vitaminlike compound has proved to be many times more potent than such old guard antioxidants as vitamins C and E. As a perk, it even recycles C and E (as well as other antioxidants), enhancing their effectiveness.

Because it dissolves in both water and fat, this so-called "universal antioxidant" is able to scavenge more wayward free-radical cells than most antioxidants, the majority of which tend to dissolve in either fat or water but not both. Alpha-lipoic acid can reach tissues composed mainly of fat, such as the nervous system, as well as those made mainly of water, such as the heart.

Also known as lipoic acid or thioctic acid, alpha-lipoic acid is mainly derived from dietary sources (spinach, liver, brewer's yeast), although scientists have discovered that the body does manufacture small supplies of its own. In order to get the concentrated doses needed to treat specific ailments, however, many experts recommend supplements.

Health Benefits

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.