Dietary antioxidants and long-term risk of dementia.
Level 3 - non-randomized controlled study
Prospective non-randomized cohort study
PubMed 20625087 · doi:10.1001/archneurol.2010.144
What was done
Researchers evaluated 5,395 dementia-free participants aged 55 years and older from the population-based Rotterdam Study in the Netherlands. Baseline dietary intake of major antioxidants (vitamin E, vitamin C, beta carotene, and flavonoids) was assessed. Participants were followed for a mean of 9.6 years to determine incident dementia and Alzheimer disease (AD) using internationally accepted criteria, adjusting for age, education, apolipoprotein E epsilon4 genotype, total energy intake, alcohol intake, smoking habits, body mass index, and supplement use.
What was found
During the mean follow-up of 9.6 years, dementia developed in 465 participants (365 with AD). Higher baseline dietary intake of vitamin E was associated with a lower long-term risk of dementia (P = .02 for trend). Participants in the highest tertile of vitamin E intake had a 25% lower risk of dementia compared with the lowest tertile (hazard ratio, 0.75; 95% confidence interval, 0.59-0.95), with similar results for AD. Dietary intakes of vitamin C (P > .99 for trend), beta carotene (P > .99 for trend), and flavonoids (P = .60 for trend) were not associated with dementia risk after multivariate adjustment.
Why it matters
This prospective cohort study suggests that higher dietary intake of foods rich in vitamin E, but not other common antioxidants, is associated with a modest reduction in the long-term risk of incident dementia and Alzheimer disease.
Limits
As an observational study, residual confounding cannot be excluded despite multivariate adjustments. Dietary intake was assessed only at baseline, potentially misclassifying exposure if diet changed over the 9.6-year follow-up. The study population was restricted to adults aged 55 and older in the Netherlands.
Cited by
- contradicts In a 10-year study of nearly 5,400 participants aged 55 and older, every 54-milligram increase in daily dietary vitamin C intake was associated with an 18% reduction in the risk of Alzheimer's disease, and a 35% reduction in smokers.