B Vitamins Did Not Prevent Alzheimer's

Alzheimer disease risk did not decrease with vitamin B consumption despite previous research

(RxWiki News) Some in the medical community have zeroed in on B vitamins as having the potential to reduce Alzheimer’s risk. But recent research suggested this hypothesis wasn't true.

New research led by a British team found no link between B vitamins like folic acid and B-12 and Alzheimer’s prevention.

"Seek medical advice if you think you are at risk for Alzheimer's."

Robert Clarke, MD, of the Clinical Trial Service Unit and Epidemiological Studies Unit at the University of Oxford in the United Kingdom, led this research.

Memory loss, behavioral changes and other effects of Alzheimer’s disease can take a heavy toll on patients and their families. Dr. Clarke and colleagues set out to analyze the “homocysteine hypothesis” as it relates to the disease.

Alzheimer’s is a progressive brain condition that impairs memory, thinking and behavior over time. High blood levels of the compound homocysteine have been found in Alzheimer’s patients and linked to an increased risk of developing Alzheimer’s.

Vitamin B-12 and folic acid can reduce homocysteine levels. This fact prompted the homocysteine hypothesis, which suggests that taking B vitamins to reduce homocysteine can reduce Alzheimer’s risk.

Dr. Clarke and team conducted a meta-analysis, meaning they reviewed 11 previously concluded clinical trials comprising some 22,000 participants.

The previous research compared the impact of B vitamins on patients' brain function to the impact of a placebo (mock vitamin supplements).

While the patients receiving B vitamins experienced a reduction in homocysteine levels, according to the study, there was no apparent effect on brain function.

The researchers found no difference between the B vitamin group and placebo group across measures of overall brain function and tests focused on memory, speed and using past experience to inform present actions (called executive function).

Dr. Clarke said in a prepared statement that the research findings discount the homocysteine hypothesis.

“Our study draws a line under the debate: B vitamins don't reduce cognitive decline as we age," Dr. Clarke said. "Taking folic acid and vitamin B-12 is sadly not going to prevent Alzheimer's disease.

“About 25 percent of the adult population take multi-vitamins, often with the idea that they are also good for the heart or the brain, but the evidence just isn't there. Much better is to eat more fruit and vegetables, avoid too much red meat and too many calories, and have a balanced diet," he said.

The findings emphasized the need for further research into the effects of Alzheimer's treatments, said Simon Ridley, PhD, and head of research for Alzheimer’s Research UK, which provided partial funding for the study, in a press release.

This study was published in the August issue of the peer-reviewed American Journal of Clinical Nutrition.

Funding was provided by the British Heart Foundation, the UK Medical Research Council, Cancer Research UK, the UK Food Standards Agency and the National Department of Health.

Review Date: 
July 22, 2014