Folate, also called folic acid or vitamin B9, plays a vital part in the proper functioning of the brain and in the synthesis of DNA and RNA. Adequate daily intake of folate is necessary for the maintenance of an individual's mental and emotional well-being. In addition, there is preliminary evidence that suggests that folate may lower the risk of developing Alzheimer's disease. Randomized clinical trials are needed to confirm this tentative finding.
Animal Study
The National Institute on Aging summarizes a study of the effects of folate in a mouse model of Alzheimer's disease. In this study, which appeared in the March 1st, 2002 issue of the "Journal of Neuroscience," researchers found that the number of nerve cells in a brain region affected by Alzheimer's disease was lower in mice that were on a folate-deficient diet relative to the number of nerve cells in mice that received sufficient folate. The researchers speculate that folate protects the nerve cells from the damage caused by Alzheimer's disease.
Human Studies
In an article that appeared in the July 2005 issue of "Alzheimer's and Dementia," researchers reported that in their study of 579 elderly subjects, consistent dietary intake of folate in amounts at or above the recommended dietary allowance was linked to a statistically significant decrease in the risk of Alzheimer's disease. In another study published in the January 2007 issue of "Archives of Neurology" and summarized in "U.S. News and World Report" magazine, scientists conclude that in a field of 965 senior citizens, those who consumed the highest amounts of folate over the six-year study period had the lowest probability of developing Alzheimer's disease.
Folate and Cholinesterase Inhibitors
Prescription medications for Alzheimer's disease are in a class of drugs called cholinesterase inhibitors. Alzheimer's disease causes the loss of nerve cells activated by the neurotransmitter acetylcholine. Cholinesterase inhibitors slow down the breakdown of acetylcholine, thereby prolonging the life of the acetylcholine-activated nerve cells. In the February 2008 issue of the "International Journal of Geriatric Psychiatry," researchers report on a six-month, double-blind, placebo-controlled study of 57 Alzheimer's disease patients with an average age of 76, all of whom were taking a cholinesterase inhibitor. The researchers found that patients who received a folate supplement with their cholinesterase inhibitor showed an enhanced response to the drug relative to patients who received only placebo with their drug.
Considerations
The human studies reported in "Alzheimer's and Dementia" and "Archives of Neurology" establish a link between folate consumption and a decreased risk of Alzheimer's disease. These studies, however, don't prove that folate is the cause of the reduced risk of getting Alzheimer's. Randomized clinical trials are required to demonstrate a cause-and-effect relationship between folate intake and lower risk of Alzheimer's.
References
- University of Maryland Medical Center: Vitamin B9 (Folic acid)
- National Institute on Aging: Folic Acid Possibly a Key Factor in Alzheimer's Disease Prevention
- "Alzheimer's and Dementia"; Reduced risk of Alzheimer's disease with high folate intake: The Baltimore Longitudinal Study of Aging; Maria M. Corrada, et al.; July 2005
- "U.S. News and World Report"; Folic Acid: A Shield Against Alzheimer's?; Michelle Andrews; January 2007
- "International Journal of Geriatric Psychiatry"; A randomised double-blind placebo-controlled trial of folic acid supplementation of cholinesterase inhibitors in Alzheimer's disease; Peter J. Connelly, et al.; February 2008
