Information about Antioxidant Vitamins and Alzheimer's Risk

Antioxidant vitamins such as vitamins C and E are being studied for potential protective effects against Alzheimer's disease. Antioxidants are substances that neutralize free radicals (damaging molecules created as the body uses oxygen). Free radicals can damage DNA within cells and are associated with several aging-related diseases, including heart disease. Some evidence indicates that free radical damage (also called oxidative stress) contributes to the brain changes seen in Alzheimer's disease.

Several large, long-term observational studies suggest that antioxidant vitamins may be beneficial in preventing dementia. For example, a study from the Archives of Neurology found that, among more than 3,000 individuals age 65 and older, those who took supplements of vitamins C and E were 64% less likely to develop Alzheimer's disease over three to five years than those who did not take the two supplements.

But not all studies support a protective effect of antioxidant supplements. One study indicated that obtaining vitamins C and E through the diet (but not in supplements) helped prevent Alzheimer's disease. Another found that overall antioxidant intake in older people (regardless of the source) did not affect the risk of Alzheimer's four years later.

While the jury is still out, we do not recommend that individuals take vitamin E supplements to forestall or prevent dementia because the weight of evidence now points away from it being beneficial. Be sure to consult with your doctor before taking vitamin E supplements, because high levels of the vitamin can cause bleeding in some people.

Publication Review By: Peter V. Rabins, M.D., M.P.H.

Published: 08 Mar 2011

Last Modified: 28 Jan 2015