This study involved 191 people with no memory problems or concerns about cognitive problems and were described by the authors as being relatively healthy and highly functioning , but with low blood B12 levels. Half the group were given placebos and half were given B vitamins. There was no change in their cognitive function after a year. Neurological tests also showed no change. That’s the gist of it.
So, if the memory of those in the placebo group, who started with good cognitive function, didn’t get any worse why would anyone expect those in the B12 group to respond any differently? If the study had been long enough for the memory of some of those in the placebo group to get worse then the trial might have shown if B12 could help prevent it. But with no change in the placebo group, you know the study is either too short, has the wrong people (eg without memory issues), using too low a dose or that the memory tests are not sufficiently sensitive.
But there is more that is seriously flawed in this research. The researchers tell us the starting (baseline) homocysteine levels and cognitive function scores of the participants. So it seems to me it would have been sensible and useful to have reported on any difference between those starting with high homocysteine versus low homocysteine, or in those starting with worse cognitive function scores.
I know that reviewers have asked for these calculations to be included in Clarke’s previous studies but, once again, these essential sub-group analyses have not been done. I did contact the lead author, Dr Alan Dangour, to ask why not. He informed me that they were prohibited from doing so, under the ‘Consort’ guidelines (which stands for the ‘Consolidated Standards for Reporting Trials’, giving researchers a set of guidelines for conducting good quality research) given that they had not pre-specified these analyses when they originally designed the trial. The Consort guidelines, however, do allow for relevant post hoc sub-group analyses to be done,. Since they are so central to the issue being researched I do not understand why they have not been done. The authors say they ‘have clear plans for the conduct and publication of such analyses’ but do not say what they are.
The net result is that the paper is meaningless. It simply shows that supplementing extra B12, if your memory is good, won’t make it better. It’s like finding no benefit from giving insulin to healthy people and concluding it wouldn’t benefit diabetics. Yet Oxford University sent out a press release ensuring the media will pick it up and run more fallacious “no benefits from B vitamins stories”. The detailed and expert criticism of the trial’s failings will no doubt be published in due course but will inevitably be ignored and so the myth will be perpetuated.
As a result people with raised homocysteine levels will be put off supplementing B12 when there is good evidence that it can help reduce the rate of brain shrinkage and memory loss in those with memory problems and raised homocysteine levels. What is still not nailed down is whether it can help prevent dementia in those without memory problems.. This study contributes no useful information at all to that question since it was far too short and no-one in the placebo group was anywhere near the diagnosis of pre-dementia.
It has been funded by the UK government. Why are we taxpayers paying for research that is clearly a total waste of money when there is a desperate need for funding for good quality prevention research?
If you’d like to see a summary of evidence for B12 and lowering homocysteine in the context of dementia prevention see www.foodforthebrain.org/hcyevidence.