January 28, 2007
People who get plenty of folate, a common B vitamin found in foods and dietary supplements, may be at reduced risk for Alzheimer's disease, researchers from Columbia University Medical Center in New York report. The findings add to a growing body of evidence that various vitamins and other nutrients may be key to brain health. It is still too early to say, however, whether folate, also called folic acid, or other nutrients may actually prevent the onset of Alzheimer's disease. The research appeared in the Archives of Neurology, a journal published by the American Medical Association.
Folate and other B vitamins, including B12 and B6, are important in the body's processing of homocysteine, an amino acid that has been linked to inflammation. Increasingly, doctors recognize that inflammation may play a key role in heart disease and strokes.
Inflammation may also lead to damage to the blood vessels in the brain, increasing the risk of Alzheimer's disease and other forms of dementia. Getting plenty of folate may alleviate inflammation and thereby lower the risk of Alzheimer's.
In the study, doctors surveyed 965 seniors about what they ate and any multivitamins or other dietary supplements they took over a six-year period. All were free from serious memory problems or other symptoms of Alzheimer's at the start of the study. Their average age was 75, and they included White, African-American, and Hispanic subjects.
During the follow-up period, 192 of the study participants developed Alzheimer's disease. The researchers found that overall, those who got the most folate, through a combination of both foods and supplements, were least likely to come down with Alzheimer's disease.
Getting more folate through either diet or supplements alone, however, did not lower the risk. This could mean that higher levels of folate (resulting from a combination of diet and supplement intake) were required to affect the risk of Alzheimer's disease. Or, it could mean that folate in combination with some other food-derived nutrient was required.
The doctors considered other factors as well, including other ailments the seniors may have had. They also looked at intake of vitamins B12 and B6, but these were not linked to lower Alzheimer's risk.
Higher folate intake was modestly correlated with lower homocysteine levels, "indirectly suggesting that a lower homocysteine level is a potential mechanism for the association between higher folate intake and a lower Alzheimer's disease risk," the authors write.
More Study Needed
The authors caution that more studies are needed to prove that what you eat may have a direct impact on whether you develop Alzheimer's disease. Dietary surveys are difficult to assess and may be unreliable. In addition, many factors play a role in the onset of Alzheimer's, including genes, advancing age, and other factors.
Still, some earlier studies suggest that B vitamins, including folic acid, may be good for the brain. In 2005, for example, researchers at the University of California at Irvine found that seniors who regularly consume the recommended daily allowance (RDA) of 400 micrograms of folic acid through foods and supplements cut their risk of developing Alzheimer's by over 50 percent.
Folic acid is plentiful in green vegetables such as broccoli, asparagus, peas, and lettuce, as well as beans, whole grains, and orange juice. Breads, pastas, rice, and flour are also commonly fortified with the nutrient. Folic acid has long been urged for pregnant women to prevent birth defects.
Many people, particularly seniors, do not get enough folic acid. Folic acid supplements, often taken as part of a multivitamin, may therefore be an important addition to a daily regimen. Many adults also take folic acid supplements to reduce their risk of cardiovascular disease.
It is still too early to say, though, whether adults should routinely take higher doses of folic acid or other nutrients as a preventive measure against memory loss or Alzheimer's. However, no one should take more than 1,000 micrograms of folic acid as a supplement. One problem with taking folic acid is that it can mask some of the symptoms of vitamin B-12 deficiency, which is common in the elderly. This can be avoided by asking your doctor to check your vitamin B-12 levels and by taking folic acid in combination with other B vitamins, including B-12. Consult your doctor before taking folic acid or other supplements.
Your best bet may be to follow a heart-healthy diet low in fats and rich in fruits and vegetables and whole grains to help maintain the brain and preserve the memory. A sound diet helps to maintain the health of the blood vessels, including those that supply oxygen and nutrients to the brain. In addition, regular exercise and mental and social stimulation is thought to be critical to keeping the mind active and alert into old age. For more on Alzheimer's and preserving the memory, visit www.ALZinfo.org, for news, updates, and background health reports.
American Medical Association, press office.
José A. Luchsinger; Ming-Xin Tang; Joshua Miller; Ralph Green; Richard Mayeux: "Relation of Higher Folate Intake to Lower Risk of Alzheimer Disease in the Elderly."Archives of Neurology, Volume 64, Number 1, January 2007; pages 86-92.