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Study: Vitamin E Corrects Nerve Damage in Mice

But experts urge caution with antioxidant

TUESDAY, Dec. 18, 2001 (HealthDayNews) -- Fruits do it, lawn chairs do it, even educated brains do it: oxidize.

"Rusty" neurons corroded by renegade oxygen atoms have been linked to Alzheimer's disease, Parkinson's and numerous other neurological disorders. But a new study by Japanese scientists says vitamin E, which mops up these so-called free radicals, can effectively eliminate cell damage in rodents that don't have the gene that helps shield them from the harmful particles.

Severe vitamin E deficiency has been linked to a rare, inherited form of ataxia, a term that describes several nerve and muscle disrupting conditions in people.

The Japanese researchers, whose work appears in the latest issue of the Proceedings of the National Academy of Sciences, created a strain of mice to mimic this disorder. The "knockout" mice were missing the gene for alpha-Tocopherol (vitamin E) transfer protein, which lets them process the vitamin. The mutation drained their brain cells and other tissues of vitamin E, leaving them especially vulnerable to harmfully charged oxygen.

Deprived of vitamin E in their diet, after about a year the animals began developing ataxia that caused them to have trouble moving. They also were prone to disintegration of their retinas, the light-sensing screens at the back of the eyes.

But when vitamin E was added to their food, the mutant animals showed almost no signs of nerve damage, the researchers say. Even amounts that hiked brain levels of the nutrient from 10 percent to 20 percent of normal were enough to essentially reverse the effects of the gene flaw.

"This therapy almost completely corrects the abnormalities in a mouse model of human neurodegenerative disease," the researchers write. "Moreover, [the mutant animals] may prove to be excellent animal models of delayed onset, slowly progressive" brain damage from oxygen attack.

But some scientists were not impressed by the latest findings. "The problem with studies like this is that they've created a condition that doesn't exist normally," says James Joseph, a Tufts University researcher who studies antioxidants and the brain. "Nobody has no vitamin E, I don't care what kind of diet you have."

Unfortunately, Joseph says the history of vitamin E research is a tale of strong lab findings and weaker showings in humans. The reason, he says, is precisely why the Japanese work generated such powerful results. "Unless you create this deficiency, you don't see a lot of effects of vitamin E" on brain cells or brain function because the body is pretty good at using whatever antioxidants it gets through food to clear damaging oxygen particles.

Dr. Tetsuo Ashizawa, a neurologist specializing in ataxia at Baylor College of Medicine, in Houston, agrees the latest work must be taken "with a caveat, there's no question about that." Still, he says the fact that that Japanese scientists achieved near total reversal of nerve symptoms with vitamin E is "impressive."

"In a human situation, you treat patients with vitamin E deficiency and can stop the progression [of nerve degeneration], but reversal of the disease is not that likely," Ashizawa says. "That part is impressive to me."

What To Do

Although it's probably safe for most people to take vitamin E supplements, high doses of the compound can worsen the risk of bleeding in those also taking aspirin and other blood thinners, Joseph says.

He says it's better to get a well-balanced diet that's rich in fruits and vegetables. Or, as he puts it, eat colorfully. Red strawberries, blueberries and green spinach are excellent sources of antioxidants which, in combination, appear to offer more protection against cell damage than high doses of a single supplement.

The National Ataxia Foundation has more information on the disorders, which afflict about 150,000 Americans.

The National Institutes of Health has a fact sheet about vitamin E.

Many vendors advertise antioxidants with extraordinary powers. Be wary of these claims. Check Quackwatch for the facts.

SOURCES: Interviews with James Joseph, Ph.D., associate professor, chief of the neuroscience laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston; Tetsuo Ashizawa, M.D., professor or neurology, Baylor College of Medicine, Houston; Dec. 18, 2001, Proceedings of the National Academy of Sciences
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