August 25, 2014
Many people take B vitamins in the hopes of warding off Alzheimer’s disease and keeping the mind sharp. But a new analysis found that taking B vitamins did not slow mental decline with aging or prevent the onset of Alzheimer’s.
The analysis reviewed data from 11 earlier studies involving more than 22,000 older men and women. Most of the participants were in their 60s or 70s and free of dementia at the start of the studies. In some of the studies, participants took B vitamins, while others took look-alike placebo pills, for an average of about five years.
B vitamins are known to promote nerve health and are critical for development of the brain and nervous system. Some earlier studies have shown that B vitamins lower blood levels of homocysteine, a protein known to raise the risk for heart disease and Alzheimer’s. People with Alzheimer’s often have high levels of homocysteine in their blood.
The current analysis found that taking B vitamins reduced levels of homocysteine by about 25 percent. But this did not translate into improved thinking and memory skills with age. The research was carried out by the B-Vitamin Treatment Trialists’ Collaboration, an international group of scientists. It was published in the American Journal of Clinical Nutrition.
“It would have been very nice to have found something different,” said Dr. Robert Clarke of Oxford University, who led the work. “Our study draws a line under the debate: B vitamins don’t reduce cognitive decline as we age. Taking folic acid and vitamin B-12 is sadly not going to prevent Alzheimer’s disease.”
“Much better is to eat more fruit and vegetables, avoid too much red meat and too many calories, and have a balanced diet,” Dr. Clarke added. Other studies suggest that a Mediterranean style diet, rich in fish, fresh fruit and vegetables, whole grains and heart-healthy olive oil, is good for the brain.
There are many types of B vitamins, and all are important for the healthy functioning of the brain and nervous system. After age 50, some people have trouble absorbing B vitamins from foods, particularly vitamin B12, and supplements are recommended. Women are advised to take folic acid before and during pregnancy to lower the risk of nerve-related birth defects in their children.
But for most people, taking B vitamin pills will do little to improve brain health or prevent the onset of Alzheimer’s disease. The findings underscore the importance of new research to find new and more effective treatments for Alzheimer’s disease.
Source: Clarke R, Bennet D, Parish S: “Effects of homocysteine lowering with B vitamins on cognitive aging: meta-analysis of 11 trials with cognitive data on 22,000 individuals.” American Journal of Clinical Nutrition, Vol. 100, August 2014, pages 657-666.