Dietary intake of antioxidant nutrients and the risk of incident Alzheimer disease in a biracial community study.

Abstract:

CONTEXT: Oxidative processes have been suggested as elements in the development of Alzheimer disease (AD), but whether dietary intake of vitamin E and other antioxidant nutrients prevents its development is unknown.

OBJECTIVE: To examine whether intake of antioxidant nutrients, vitamin E, vitamin C, and beta carotene is associated with incident AD.

DESIGN, SETTING, AND PARTICIPANTS: Prospective study, conducted from 1993 to 2000, of individuals selected in a stratified random sample of community-dwelling residents. The 815 residents 65 years and older were free of AD at baseline and were followed up for a mean of 3.9 years. They completed food frequency questionnaires an average of 1.7 years after baseline.

MAIN OUTCOME MEASURE: Incident AD diagnosed in clinical evaluations with standardized criteria.

RESULTS: Increasing vitamin E intake from foods was associated with decreased risk of developing AD after adjustment for age, education, sex, race, APOE epsilon 4, and length of follow-up. Relative risks (95% confidence intervals (CIs) from lowest to highest quintiles of intake were 1.00, 0.71 (0.24-2.07), 0.62 (0.26-1.45), 0.71 (0.27-1.88), and 0.30 (0.10-0.92) (P for trend =.05). The protective association of vitamin E was observed only among persons who were APOE epsilon 4 negative. Adjustment for other dietary factors reduced the protective association. After adjustment for baseline memory score, the risk was 0.36 (95% CI, 0.11-1.17). Intake of vitamin C, beta carotene, and vitamin E from supplements was not significantly associated with risk of AD.

CONCLUSION: This study suggests that vitamin E from food, but not other antioxidants, may be associated with a reduced risk of AD. Unexpectedly, this association was observed only among individuals without the APOE epsilon 4 allele.