August 15, 2005
Getting enough folic acid, a B vitamin critical for brain and nerve health, may help ward off Alzheimer's in old age, a new study from the University of California at Irvine reports. Men and women age 60 and up who regularly consumed the daily recommended daily allowance (RDA) of 400 micrograms (mcg) of folic through foods and supplements cut their risk of developing the brain-ravaging illness by over 50 percent. It is still too early to say, however, whether folic acid also called folate or other nutrients may actually prevent the onset of Alzheimer's disease.
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. The nutrient also helps reduce levels of homocysteine, a substance produced by the body that has been linked to heart disease.
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. In the current study, most of the seniors who obtained the daily RDA of 400 micrograms for folic acid did so through a combination of eating foods and taking dietary supplements. The study appeared in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.
Growing Body of Evidence
The study adds to a growing body of evidence that a nutrient-rich diet containing folic acid and other B vitamins may help preserve memory. Earlier this year, Dutch researchers reported that older adults who took high doses of folic acid supplements (800 micrograms a day) were less likely to suffer from failing memory as they aged. In the current study, however, doses above the daily RDA of 400 micrograms did not seem to provide additional benefit. In a study from 2004, researchers from the U.K. and Sweden reported that seniors who had low levels of another B vitamin, B-12, were more likely to suffer from memory problems.
Still, many questions about diet and prevention of Alzheimer's remain unanswered. "It is possible that other factors may be responsible for the reduction in risk," cautions study leader Dr. Maria Corrada. "People with a high intake of one nutrient are likely to have a high intake of several nutrients, and may generally have a healthy lifestyle. Additional studies are necessary to determine whether folate has a direct, causal role in risk reduction for Alzheimer's and to determine appropriate recommendations."
What the Study Showed
The researchers examined data from 579 men and women age 60 and older who were enrolled in the Baltimore Longitudinal Study of Aging, an ongoing research project that has followed participants for decades to look for factors that may contribute to healthy aging. None of the people had Alzheimer's or other forms of dementia at the start of the study. The study participants were surveyed regularly about what they ate and what vitamins they took. They were also given mental exams to look for signs of Alzheimer's.
After a follow-up period lasting up to 14 years (average 9 to 10 years), 57 of the study participants had developed Alzheimer's. The researchers found that those men and women who got the most folic acid, or folate, from foods and supplements were less likely to develop Alzheimer's. Those who got 400 micrograms or more of folic acid daily had a 55 percent reduction in the risk of developing the disease. Consuming higher amounts of vitamin E and another B vitamin, B-6, also seemed to reduce risk somewhat, but the benefits were not statistically significant.
The researchers suggest that folic acid's potential benefits may be linked to its effects on homocysteine. First, folic acid helps to reduce levels of homocysteine, and high levels of this substance can damage the heart and blood vessels, including the blood vessels that nourish the brain. Second, some studies in animals suggest that high levels of homocysteine and low levels of folic acid may make brain cells more vulnerable to damage from beta-amyloid, a toxic protein that has been linked to Alzheimer's. Finally, homocysteine itself may be directly toxic to brain cells.
Based on the results of these and other studies, it is still too early to say whether adults should routinely be taking higher doses of folic acid or other B vitamins as a preventive measure against memory loss or Alzheimer's. Many adults already take folic acid supplements to reduce their risk of cardiovascular disease. However, no one should take more than 1000 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.
Maria Corrada, Sc.D., Claudia Kawas, M.D., et al: "Reduced Risk of Alzheimer's Disease with High Folate Intake: The Baltimore Longitudinal Study of Aging." Alzheimer's & Dementia: The Journal of the Alzheimer's Association. Volume 1, Number 1, July 2005