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The role of B vitamins in those with Mild Cognitive Impairment

University of Oxford researcher and Professor Emeritus of Pharmacology, David Smith is currently in Australia meeting with collaborators and discussing his research on the benefits of nutrition on brain health.

Dementia News attended a presentation on his current research related to how B vitamins might help slow, or even modify the disease process in people with a Mild Cognitive Impairment (MCI).

Professor Smith presented findings from a clinical trial known as VITACOG. This randomised controlled trial included 270 participants aged 70 years or older who have a diagnosis of MCI. Each day, for two years, participants were asked to take either a B vitamin supplement (i.e. folic acid, vitamins B6 and B12) or a placebo tablet.

Professor Smith’s research group hypothesised that high-doses of B vitamins could slow down brain atrophy in people with MCI.

“We discovered that a molecule found in the blood, called homocysteine, was strongly influenced by levels of B vitamins in the blood and secondly, that homocysteine levels were closely linked to brain degeneration,” Professor Smith said.

So before we go into more detail, let’s go back a step and find out more about homocysteine.

What is homocysteine?

Homocysteine is an amino acid found in the blood. Amino acids are the building blocks of all the proteins in our body. We know that homocysteine and methionine (another amino acid) are intimately interconnected and interdependent upon each other. They form part of the so-called methionine cycle which is strongly influenced by the intake of B vitamins. For example, if a person ingests lots of protein, and there is not enough folic acid, B6 and B12 available to help digest it, homocysteine levels can build up in the blood stream. Suggesting that raised homocysteine levels are predominately seen in those with a low vitamin B intake.

How is homocysteine linked to dementia?

Professor Smith spoke about multiple studies that have found raised homocysteine levels (as measured in the blood) can:

  • Initiate cognitive impairment and poor brain performance,
  • Increase the incidence of dementia,
  • Increase the conversion of those with MCI to dementia,
  • Increase white matter hyperintensities and neurofibrillary tangles in the brain and
  • Increase the rate of shrinkage in the brain

In particular, a 2005 study followed 816 participants (average age 74) for up to four years. Of these, 112 developed dementia during their follow sessions and these people all had elevated levels of homocysteine.

The VITACOG trial

In an article published last year in the Journal PNAS, Professor Smith and his research team found that treatment for two years with B vitamins could slow brain atrophy by 30%. BUT! this effect was highly depended upon the person’s baseline level of homocysteine. Specifically, only those who had high levels of homocysteine at the beginning of the study showed a slowing of brain atrophy as a result of B vitamin supplementation.

Professor Smith said he was surprised by the prominent effects seen in the various subgroups involved in the trial.

“We also noted that participant’s omega 3 levels also played a large role in the results. For example, B vitamin supplementation was found to not have an effect on slowing brain atrophy, if the person’s omega 3 levels were low or poor. Leading us also to hypothesise that vitamin B supplementation may only be effective if your omega 3 status is also good.”

He went on to say:

“Our results have intensified the need for further trials so we can clarify these results further.”

Professor Smith now plans to undertake trials focusing on older adults with high homocysteine levels to see if progression to dementia could be prevented through B vitamin supplementation.

Summary

While these results are exciting and show promise, it is important to remember that this research does not currently suggest that B vitamin supplementation can reduce your risk of dementia in healthy adults, nor does it suggest B vitamins as a treatment for people with dementia. With further research, it may be possible however to develop guidelines for supplementation among specific groups of people with MCI, dependent on other factors such as their homocysteine or omega 3 levels.

Alzheimer’s Australia recommends that people eat a variety of foods to ensure a balanced diet that meets nutritional needs, including adequate folate and Vitamin B12 intake. However, if you do want to add vitamin supplements to your diet, please do consult a health professional before doing so.

For more information on this topic and other dementia risk reduction techniques, Alzheimer’s Australia recommends visiting www.yourbrainmatters.org.au.

Sources: 

ANU Public Lecture abstract - http://billboard.anu.edu.au/event_view.asp?id=107972
PNAS - http://www.pnas.org/content/early/2013/05/16/1301816110

Image taken from University of Oxford website

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