April 11, 2003 -- Alpha lipoic acid, an over-the-counter antioxidant supplement, eases the burning, pain, and numbness associated with diabetic neuropathy, say researchers. In a new study, alpha lipoic acid offered quick and dramatic relief without the side effects of drugs currently used.
After just 14 treatments, patients with diabetic neuropathy who received high doses of intravenous alpha lipoic acid had a threefold improvement in pain, numbness and other symptoms compared with those treated with placebo.
"But it didn't act only as a pain medication," says researcher and Mayo Clinic neurologist Peter Dyck, MD. "Alpha lipoic acid seems to actually change the metabolism of the nerve or blood supply to the nerve, and we noted some relief in symptoms."
His study, reported in the March issue of Diabetes Care, involved 120 patients with the most common form of diabetic neuropathy, which causes pain, numbness, and a burning sensation and often leads to foot problems.
Half of the patients received five treatments a week consisting of 600 mg of alpha lipoic acid in intravenous form, while the others got a placebo. They didn't know which substance they received. In just 2½ weeks, the alpha lipoic acid patients reported -- and the researchers noted in examinations -- dramatic improvements in symptoms, including a six-point drop in pain levels on a 10-point scale. The placebo group reported a two-point improvement in pain relief.
Alpha lipoic acid is available over-the-counter in dosages of 50 to 150 mg. Dyck is currently conducting a study measuring the efficacy of those capsules in other diabetic patients. The powerful antioxidant has been used for nearly 30 years in Europe to treat diabetic neuropathy and is being studied in the U.S. as a treatment for HIV, Parkinson's disease, Alzheimer's disease, and other conditions.
"I'm glad to see we have now jumped the Atlantic and the evidence gathered by German researchers decades ago has been read and is being considered by prominent American researchers," says Richard A. Passwater, PhD, retired biochemist who has studied antioxidant treatments since the 1960s and wrote the book, Lipoic Acid: The Metabolic Antioxidant. He says that he is not surprised by Dyck's findings.
Dyck, who conducted the study with Russian researchers, says that alpha lipoic acid offered several benefits to his patients with diabetes. "It is a very strong antioxidant and it is assumed that oxidation plays a role in the development of diabetes," he tells WebMD. This means the substance -- produced in very small amounts by the body and also found in foods such as potatoes and red meat -- protects against damage by cell-ravaging "free radicals." This oxidation process is implicated in various diseases, including heart disease, cancer, and neurologic conditions including Parkinson's and Alzheimer's.
"Besides that, alpha lipoic acid also seems to promote better blood flow and oxygen to the nerves and may also promote the entry of glucose and the breakdown of it into cells," he says.
Passwater says this is because alpha lipoic acid improves the function of cell "transporters" that carry and distribute glucose. "This helps insulin do its role," he tells WebMD. "It also has a specific effect on nerves that we don't know too much about but have noted. Overall, it has universal benefits, affecting various body sites, and works with other antioxidants to help them protect the body."
Though hundreds of studies have been done on alpha lipoic acid -- including several that suggest a benefit in treating diabetic neuropathy in patients with both type 1 and type 2 diabetes -- few large trials have been conducted in the U.S. In several foreign studies on mice and people, dosages ranging from 60 mg to 800 mg seemed to produce improvements in blood sugar levels and insulin production and decrease diabetic neuropathy pain.
Diabetic neuropathy is currently treated with painkillers, including narcotics -- which can be habit-forming -- and antiepileptic drugs, which can cause sedation. Alpha lipoic acid, meanwhile, appears to be safe and has few side effects, says Dyck.
But he isn't suggesting that people with diabetes self-medicate themselves with alpha lipoic acid. "We're not quite at that stage; we first need to complete studies using the oral capsules. If you have diabetes, the first line of treatment is glucose control," Dyck tells WebMD. "But the reality is that some people cannot or will not get desired control of blood sugar. And if further research proves conclusive, it looks as though alpha lipoic acid might be one of the ways they can do it."