Alpha-lipoic acid is an antioxidant that is made by the body and is found in every cell, where it helps turn glucose into energy. Antioxidants attack “free radicals,” waste products created when the body turns food into energy. Free radicals cause harmful chemical reactions that can damage cells in the body, making it harder for the body to fight off infections. They also damage organs and tissues.
Other antioxidants work only in water (such as vitamin C) or fatty tissues (such as vitamin E), but alpha-lipoic acid is both fat- and water-soluble. That means it can work throughout the body. Antioxidants in the body are used up as they attack free radicals, but evidence suggests alpha-lipoic acid may help regenerate these other antioxidants and make them active again.
In the cells of the body, alpha-lipoic acid is changed into dihydrolipoic acid. Alpha-lipoic acid is not the same as alpha linolenic acid, which is an omega-3 fatty acid that may help heart health (See also: Alpha linolenic acid.) There is confusion between alpha-lipoic acid and alpa linolenic acid because both are sometimes abbreviated ALA. Alpha-lipoic acid is also sometimes called lipoic acid.
The ability of alpha-lipoic acid to kill free radicals may help people with diabetic peripheral neuropathy, who have pain, burning, itching, tingling, and numbness in arms and legs from nerve damage.
Alpha-lipoic acid has been used for years to treat peripheral neuropathy in Germany. Most of the studies that have found it helps have used intravenous (IV) alpha-lipoic acid, however. It’s not clear whether taking alpha-lipoic acid by mouth will help. Most studies of oral alpha-lipoic acid have been small and poorly designed. One 2006 study did find that taking alpha-lipoic acid for diabetic neuropathy reduced symptoms compared to placebo.
Taking alpha-lipoic acid may help another diabetes-related condition called autonomic neuropathy, which affects the nerves to internal organs. One study found that 73 people with cardiac autonomic neuropathy, which affects the heart, showed fewer signs of the condition when taking 800 mg of alpha-lipoic acid orally compared to placebo.
Brain Function and Stroke
Because alpha-lipoic acid can pass easily into the brain, it may help protect the brain and nerve tissue. Researchers are investigating it as a potential treatment for stroke and other brain problems involving free radical damage, such as dementia. So far, there’s no evidence to say whether it works or doesn’t.
Some preliminary studies suggest alpha-lipoic acid may help treat glaucoma, but there is not enough evidence to say for sure whether it works. In one study on aging skin, a cream with 5% lipoic acid helped reduce fine lines from sun damage.