Dietary Antioxidants May Keep Dementia at Bay

Megan Brooks

September 19, 2012

September 19, 2012 — Dietary antioxidants, specifically vitamin C and beta-carotene, may protect older adults against dementia, new research suggests.

A population-based case-control study showed that elderly adults with dementia had significantly lower blood levels of vitamin C and beta-carotene than their cognitively healthy peers.

"As the consumption of fruit and vegetables is widely recommended for prevention of chronic diseases, our findings suggest that these public health initiatives...may be beneficial in reducing the prevalence of cognitive impairment in older subjects," study investigator Gabriele Nagel, MD, from the Institute of Epidemiology and Medical Biometry, Ulm University, in Germany, told Medscape Medical News.

Dr. Gabriele Nagel

"Results from experimental research support the idea that antioxidants protect against neurodegeneration, (and) epidemiological data support a relation between the use of antioxidants and risk for dementia," she added.

Reached for comment, Maria Carrillo, PhD, senior director of medical and scientific relations for the Alzheimer's Association, who was not involved in the study, told Medscape Medical News: "This is an interesting but quite small study, and it is cross-sectional only — that is, it is a snapshot in time rather than following the participants over time — so we can't draw any conclusions from the results."

The findings are published in the September issue of the Journal of Alzheimer's Disease.

Population-Based Study

To investigate further, Dr. Nagel, first author Christine A. F. von Arnim, MD, and colleagues evaluated serum levels of vitamin C, vitamin E, beta-carotene, lycopene, and coenzyme Q10 in 74 adults with mild dementia (Mini–Mental State Examination score of 24 or lower) and 158 cognitively healthy age- and sex-matched control participants. The average age of study participants was 78.9 years.

Dr. Christine von Arnim

After adjusting for education, use of dietary supplements, smoking, body mass index, and alcohol use, those with dementia had significantly lower blood vitamin C and beta-carotene levels.

The adjusted odds ratio (OR) for the third vs first tertile of vitamin C (74.4 vs 28.9 µmol/L) was 0.29 (95% confidence interval [CI], 0.09 - 0.96). For beta-carotene (0.8 vs 0.2 µmol/L), the adjusted OR was 0.13 (95% CI, 0.03 - 0.55).

No associations were found for the other antioxidants (vitamin E, lycopene, and coenzyme Q10).

"The population-based approach of our study increases the generalization of our results to other similar populations and is not limited to a highly selective patient population," said Dr. Nagel.

However, the researchers note that the study is limited by its cross-sectional character, and long-term data are needed to get a better understanding of these associations.

Dr. Carrillo agreed that the findings of this study should be interpreted cautiously.

"They do not demonstrate causation. We do not know from this data if Alzheimer's disease causes the changes in the levels of vitamin C and beta-carotene, or the other way around. This type of research does not address that question but only shows us that there is some sort of an association between the disease and the antioxidant levels. That is not yet enough information to talk about therapeutic activity or response. What's needed next are studies in larger and more diverse population over time," she said.

The study was funded by a grant from the Ministry of Science, Research and Arts, state of Baden-Wuerttemberg, Germany, as part of the Geriatric Competence Center. Author disclosures are available on the journal's Web site.

J Alzheimers Dis. 2012;31:717-724. Abstract