Peter P. Zandi, PhD, lead author of the study and an assistant professor in the School's Department of Mental Health, said, "These results are extremely exciting. Our study suggests that the regular use of vitamin E in nutritional supplement doses, especially in combination with vitamin C, may reduce the risk of developing Alzheimer's disease."
The researchers examined data from the Cache County Study, which is a large, population-based investigation of the prevalence and incidence of Alzheimer's disease and other dementias. Residents who were 65 or older were assessed from 1996-1997 and again from 1998-2000. Study participants were asked at their first contact about vitamin usage. The researchers then compared the subsequent risk of developing Alzheimer's disease over the study interval among supplement users versus nonusers to come to their conclusions.
Approximately 17 percent of the study participants reported taking vitamin E or C supplements. These individuals were significantly more likely to be female, younger, better educated and reported better general health when compared to non-supplement users. In addition to those who took vitamin supplements, another 20 percent of study participants used multivitamins, but without a high dosage of vitamin E or C.
The researchers found a trend towards reduced Alzheimer's disease with a combination of vitamin E and C supplements, even after controlling for age, sex, education and general health. However, there was no notable reduction in the risk of Alzheimer's disease with vitamin E or vitamin C alone or with multivitamins. Multivitamins typically contain the recommended daily allowance of vitamin E (22 IU or 15 mg) and vitamin C (75-90 mg), while individual supplements contain doses up to 1,000 IU of vitamin E and 500-1,000 mg or more of vitamin C.
The researchers explained that the use of vitamins E and C may offer protection against Alzheimer's disease when taken together in the higher doses available in individual supplements. In addition, there may be some protective effect with vitamin E when it is combined with the lower doses of vitamin C found in multivitamins.
Dr. Zandi said, "Further study with randomized prevention trials is needed before drawing firm conclusions about the protective effects of these antioxidants. Such trials should consider testing a regimen of vitamin E and C in combination. If effective, the use of these antioxidant vitamins may offer an attractive strategy for the prevention of Alzheimer's disease."
The study was funded by grants from the National Institutes of Health and National Institute of Mental Health. The Bryan Alzheimer's Disease Center at Duke University completed the APOE genotyping.
James C. Anthony, Ara S. Khachaturian, Stephanie V. Stone, Deborah Gustafson, JoAnn T. Tschanz, Maria C. Norton and John C. S. Breitner co-authored the study.
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