Using repeated and validated dietary assessments of two large study cohorts, researchers from Harvard School of Public Health, Brigham and Women's Hospital, and Harvard Medical School examined the associations between dietary intakes of vitamin E, C, and carotenoids, vitamin supplements, and risk of Parkinson's disease. After exclusions, 76,890 women from the Nurses' Health Study (NHS) and 47,331 men from the Health Professionals Follow-Up Study (HPFS) were included in the study analyses.
Dietary data was collected from the women's cohort since 1984 and from the men's since 1986. The food frequency questionnaires used in the NHS and HPFS have been validated and shown to reflect reasonably the long-term nutrient intakes of study participants. In addition to dietary assessments, questions on the use of specific vitamins and brand and type of multivitamins were asked. By 1998, the end of the study term, a total of 371 new cases of Parkinson's disease (161 in women and 210 in men) were documented.
"In these two large cohorts, we found no evidence that use of vitamin E or C supplements or multivitamins reduced the risk of Parkinson's," says study author Shumin Zhang, MD, ScD, Harvard School of Public Health and Harvard Medical School. "In contrast, however, higher intake of dietary vitamin E was associated with a significantly lower risk of Parkinson's."
Dr. Zhang notes, however, that the participants in both the NHS and HPFS are a self-selected group of individuals who may have healthier diets and lifestyles than average Americans. Therefore, the lower risk of Parkinson's associated in this study with high dietary vitamin E intake may also be attributable to other unidentified dietary or lifestyle factors.
The study was supported by a research grant from the National Institutes of Health.
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