Vitamins C and E may help reduce risk of Alzheimer’s disease
Antioxidants, such as vitamins C and E, help fight disease by protecting the body's cells from damage. They occur naturally in a variety of fruits, vegetables, grains, legumes, and nuts. Research has suggested that antioxidants in general may play a role in helping protect brain cells from Alzheimer’s disease, but the evidence has been conflicting. Now, research published in the June 26, 2002 issue of the Journal of the American Medical Association (JAMA) suggests that foods rich in vitamins C and E may be particularly effective in reducing your risk of Alzheimer’s disease.
About the study
Researchers from Erasmus Medical Center in Rotterdam, the Netherlands studied 5395 men and women in The Rotterdam Study—an ongoing study of disease among elderly people in Rotterdam. Participants were aged 55 or older and free of dementia when they entered the study between 1990 and 1993. People were excluded if they lived in a nursing home or other institution or did not complete a dietary questionnaire when they entered the study.
Upon entering the study, participants underwent medical and mental status examinations and completed dietary questionnaires. They also answered questions about their current and past health, medication, lifestyle, and risk factors for chronic diseases. Medical and mental examinations were repeated in 1993-94 and 1997-99. In addition, researchers used a computer linkage system to monitor participants’ medical records throughout the study.
After an average of 6 years of follow-up, researchers compared the intake of antioxidants (including vitamins C and E) among participants who developed Alzheimer’s disease and those who did not.
Compared with people who consumed the least vitamin E-rich foods, those who consumed the most were 43% less likely to develop Alzheimer’s disease. And people who ate the most vitamin C-rich foods were 34% less likely to develop Alzheimer’s disease than their counterparts who ate the least vitamin C-rich foods. Of interest is that taking antioxidant supplements did not seem to affect the risk of Alzheimer’s disease.
In calculating theses statistics, the researchers accounted for the following factors that affect the risk of Alzheimer’s disease: age, sex, mental status (at the start of the study), alcohol intake, smoking, body mass index, education, use of antioxidant supplements, APOE4 gene mutation (thought to be an indicator of Alzheimer’s disease), and plaque in the carotid artery. Of note is that smokers seemed to benefit more from higher vitamin C and E intake than nonsmokers.
Although these results are interesting, there are limitations to this study. First, dietary intake of antioxidants was only assessed once at the beginning of the study. This may not accurately reflect intake over time. Second, Alzheimer’s disease progresses slowly and small changes in cognitive ability, which may be present long before diagnosis (even before the study began), could affect dietary habits and reporting of dietary intakes. Third, for participants who took supplements, no information was available regarding dosage and duration of antioxidant supplements. Without this information, the role of supplements remains unclear.
How does this affect you?
The findings of this study suggest you should make sure to eat foods with vitamins C and E, because it may help you ward off Alzheimer’s disease. Remember, this study found that foods containing these antioxidants, rather than vitamin supplements, were associated with a lower risk of Alzheimer’s disease.
Regardless of Alzheimer’s disease risk, vitamins C and E and other antioxidants are part of a balanced diet. There’s certainly no down side to eating antioxidant-rich foods, since antioxidants are believed to help ward off a number of diseases, including cancer.
Good food sources of vitamin C include:
- Citrus fruits and juices
Good food sources of vitamin E include:
- Egg yolk
Note: In the same issue of JAMA , another study reported that vitamin E, but not vitamin C, intake was associated with a lower risk of Alzheimer’s disease. See: ]]>“Vitamin E intake may reduce risk of Alzheimer’s disease.”]]> Are you confused about why two studies in the same journal would report different results? This is yet another indication that science is an ever-evolving process and that it may take years to learn the “truth.”
Engelhart MJ, et al. Dietary intake of antioxidants and risk of Alzheimer disease. Journal of the American Medical Association. June 26, 2002;287(24):3223-3229.
Foley DJ and White LR. Dietary intake of antioxidants and risk of Alzheimer disease. Journal of the American Medical Association. June 26, 2002;287(24):3261-3263.
Last reviewed June 26, 2002 by ]]>Richard Glickman-Simon, MD]]>
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