Alzheimer's Disease

Can Vitamin B12 Prevent Alzheimer’s?

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Alzheimer’s disease is one of the most feared illnesses in the world, and it has long been suspected that taking B-vitamins might help to prevent it, or could even be a miracle cure.

Why Should B12 Help?
The theory is based on the proven connection between dementia and a chemical called homocysteine. We know that having high levels of homocysteine in the blood is an important risk factor for Alzheimer’s (and possibly also strokes and coronary heart disease). And one way to lower homocysteine levels is to increase your intake of B12 and/or B9 (aka folate/folic acid).

With this knowledge of the science, it makes sense to presume that higher levels of B12 in the blood should put you at lower risk of developing Alzheimer’s.

Alzheimer's DiseaseWhat’s the Evidence?
There have been quite a few scientific studies set up to try to establish whether or not this plays out in reality. Hope hit an all-time high in 2010, when research concluded that taking high doses of B-vitamins (including B12) slows ‘brain shrinkage‘ in the elderly. As brain shrinkage is closely associated with Alzheimer’s, this was excellent news.

The scientists involved in this study pointed out at the time that the sample size was small (less than 300 people). This meant that they didn’t have enough evidence to establish any more than a connection – it was not yet undeniable fact.

The Latest Research
This caution was disappointingly prescient.Dementia A 2014 clinical review of 11 different medical trials including a total of 22,000 patients unfortunately brought bad news.

In the words of the leader of the study, Dr Robert Clarke of Oxford University, “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.”

The study compared the effects of taking B vitamins against a control group who were given a placebo. While those given the vitamins did experience significantly lowered homocysteine levels, this had no measurable effect on dementia.

B12 SupplementsThere is no strong evidence that taking B12, folate or any other B vitamin will prevent Alzheimer’s or even slow down cognitive decline in the elderly. Once you drop to any particular level of cognitive function because of age, no amount of B12 is going to restore it.

What You Can Do Instead
At the time of writing, the best advice is to keep your homocysteine levels within a healthy range, eat a good, balanced diet, take regular exercise and keep your cholesterol and blood pressure in check, particularly during middle age.

Is It Definitely Alzheimer’s?
The only vaguely good news is that some of the early symptoms of Alzheimer’s may also be present in patients suffering from unchecked vitamin B12 deficiency. Simple supplementation should then be enough to relieve the symptoms.

DiagnosisSo if you’re experiencing personality changes and an impaired memory, you should get yourself checked out by a doctor as soon as possible. There are many things that could be causing it, not just Alzheimer’s. And some of the possible causes – including B12 deficiency – are potentially reversible.

There’s also a small amount of evidence (and hope) that taking B12 supplements could help to slow or prevent certain other, rarer types of dementia. But much more research is needed before anything can be proven conclusively.

Further Reading/Watching
If you’d like to find out more about Alzheimer’s disease and dementia, please take a look at the Alzheimer’s Association or the Alzheimer’s Research Center.

Or for the best six minute overview you’re ever going to find, check out this video below.

From top to bottom, images are courtesy of ddpavumba, David Castillo Dominici, sixninepixels, and Stuart Miles, all at

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