Taking B vitamins doesn’t slow mental decline as we age, nor is it likely to prevent Alzheimer’s disease, a study by researchers at Oxford University has concluded.
Lead researcher, Dr Robert Clarke, went as far as saying that the study “draws a line under under the debate” on B vitamins and cognitive decline.
The Oxford University team wanted to test what it calls the “homocysteine hypothesis”.
High levels of homocysteine have been found in the blood of 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, leading to the view that taking B vitamins could reduce the risk of Alzheimer’s disease.
The Oxford 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. While participants receiving B vitamins did see a reduction in the levels of homocysteine in their blood by around a quarter, this had no effect on their mental abilities.
When the researchers gave scores for specific mental processes, such as memory, speed and decision-making, they found no difference between those on B vitamins and those receiving a placebo.
Clarke said:“It would have e been very nice to have found something different. Our study draws a line under the debate: B vitamins don’t reduce cognitive decline as we age. Taking folic acid and vitamin B12 is sadly not going to prevent Alzheimer’s disease.”
“Taking supplements like B vitamins doesn’t prevent heart disease, stroke or cognitive decline,” added Clarke. “About 25–30% 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 and havr a healthy diet.”
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.” But he added that “research into how to prevent Alzheimer’s must continue.”
But industry has questioned the value of a study that specifically excluded people with a prior diagnosis of Alzheimer’s or memory problems. The nutritionist and director of the Brain Bio Centre, Patrick Holford, said that the design of the Oxford study “made it incapable” of showing the benefits of B vitamins for at risk groups that had been demonstrated by prior studies.
Commenting on the study, which is published in the American Journal of Clinical Nutrition, Graham Keen, executive director of the Health Food Manufacturers Association (HFMA) said: “A fundamental issue with this study from Oxford University is that in claiming that food supplements do not help with cognitive decline, the trials reviewed actually excluded any persons with a prior diagnosis of Alzheimer disease or cognitive impairment.
“In addition, by looking at this study in isolation it does not acknowledge pre-existing, robust evidence demonstrating the positive impact of food supplements in a range of areas – including cognitive function. For example, there have been less than eight positive EU health claims approved for vitamin B12 alone, including one for Homocysteine metabolism and another for psychological function, each supported by robust research.”
“Further, the benefits of omega-3 supplements have been acknowledged by having the claim ‘contributes to maintenance of normal brain function’ approved by EU law and supported by the European Food Safety Authority (EFSA). A large-scale study published in the Neurology Journal showed that those who consumed the most omega-3 had the highest scores in tests for memory, speed, processing complicated information and overall cognitive function.”