Tuesday, July 22, 2014
Taking B vitamins doesn't slow mental decline as we age, nor is it likely to prevent Alzheimer's disease, conclude Oxford University researchers who have assembled all the best clinical trial data involving 22,000 people to offer a final answer on this debate.
High levels in the blood of a compound called homocysteine have been found in people with Alzheimer's disease, and people with higher levels of homocysteine have been shown to be at increased risk of Alzheimer's disease. Taking folic acid and vitamin B-12 are known to lower levels of homocysteine in the body, so this gave rise to the 'homocysteine hypothesis' that taking B vitamins could reduce the risk of Alzheimer's disease.
The new analysis was carried out by the B-Vitamin Treatment Trialists' Collaboration, an international group of researchers led by the Clinical Trial Service Unit at the University of Oxford. The researchers brought together data from 11 randomised clinical trials involving 22,000 people which compared the effect of B vitamins on cognitive function in older people against placebo. Participants receiving B vitamins did see a reduction in the levels of homocysteine in their blood by around a quarter. However, this had no effect on their mental abilities.
‘It would have been very nice to have found something different,’ says 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.’
Professor Clarke said, 'About 25% 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 is not there. Much better is to eat more fruit and vegetables, avoid too much red meat and too many calories, and have a balanced diet. Having a healthy diet will benefit in the long run.’
Dr Simon Ridley, Head of Research at Alzheimer's Research UK, said:
'Although one trial in 2010 showed that for people with high homocysteine, B vitamins had some beneficial effect on the rate of brain shrinkage, this comprehensive review of several trials shows that B vitamins have not been able to slow mental decline as we age, nor are they likely to prevent Alzheimer's.
Alzheimer's is feared by many and it's natural that people want to take action to try to prevent the disease, but people should always speak to their General Physician before changing their diet to include vitamin supplements. Eating a healthy, balanced diet, taking regular exercise and keeping blood pressure and weight in check can all help lower the risk of Alzheimer's.'
'One in three people over the age of 65 will develop dementia and yet research funding lags behind other conditions and we haven't seen a new treatment made available in a decade. We need to see significantly more investment and recruit the next generation of leaders in research in order to deliver breakthroughs that could prove so vital to those affected by the condition.'