According to the article, the public health threat of AD will continue to grow as people live longer. Previous studies have shown that antioxidant vitamins may protect the brain against damage caused by free radicals and other reactive oxygen species – molecular byproducts of basic cellular metabolism. Neurons are especially sensitive to damage caused by free radicals, which is believed to be partially responsible for the development of AD. Incorporating antioxidants (which help to neutralize these free radicals) into the diet through food or supplementation may help protect neurons.
Peter P. Zandi, Ph.D., of The Johns Hopkins University Bloomberg School of Public Health, Baltimore, and colleagues examined the relationship between antioxidant supplement use and risk of AD.
The researchers assessed the prevalence of dementia and AD in 4,740 elderly (65 years or older) residents of Cache County, Utah in 1995 to 1997 and collected information about supplement use. These residents were followed-up in 1998 to 2000 for new cases of dementia or AD. The researchers identified 200 cases of AD (prevalent cases) between 1995 and 1997, and 104 new cases (incident cases) of AD during follow-up.
The researchers categorized participants as vitamin E users if they reported taking an individual supplement of vitamin E or a multivitamin containing more than 400 IU (international units) of vitamin E. Vitamin C users reported taking vitamin C supplements or multivitamins containing at least 500 micrograms of ascorbic acid. Individuals were classified as multivitamin users if they reported taking multivitamins containing lower doses of vitamin E or C.
The researchers found the greatest reduction in both prevalence and incidence of AD in participants who used individual vitamin E and C supplements in combination, with or without an additional multivitamin. "Use of vitamin E and C (ascorbic acid) supplements in combination reduced AD prevalence [by about 78 percent] and incidence [by about 64 percent]," the authors write.
The researchers also found "no appreciable association with the use of vitamin C alone, vitamin E alone, or vitamin C and multivitamins in combination," and prevalence of AD.
"The current… recommended daily allowance for vitamin E is 22 IU (15 micrograms), and for vitamin C (ascorbic acid), 75 to 90 micrograms," the researchers write. "Multivitamin preparations typically contain these approximate quantities of both vitamins E and C (more vitamin C in some instances), while individual supplements typically contain doses up to 1,000 IU of vitamin E and 500 to 1,000 micrograms or more of vitamin C (ascorbic acid). Our findings suggest that vitamins E and C may offer protection against AD when taken together in the higher doses available from individual supplements."
To contact Peter P. Zandi, Ph.D., call Kenna Brigham at 410-955-6878.
(Arch Neurol. 2004;61:82-88. Available post-embargo at http://www.archneurol.com) Editor's Note: This study was supported by grants from the National Institutes of Health, Bethesda, Md., and a grant from the National Institute of Mental Health, Bethesda, Md.
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Archives of Neurology