Several studies show benefit of taking a daily B vitamin in Alzheimer’s prevention

In Alzheimer's, the cerebral cortex is reduced and the ventricles inside the brain grow larger. The brain shrinks (this is called cerebral atrophy).

It occurs seven times more quickly in someone with Alzheimer’s as it does in a healthy person of the same age.

One identifiable factor in the lead up to Alzheimer’s is increasingly high levels of homocysteine.

Homocysteine can lead to histone blockages around your DNA, as it causes methylation increasing the bonding of the histones. In effect, in Alzheimer’s, homocysteine causes tangles in the brain structure according to Helga Refsum, Professor of Molecular Nutrition at the Institute of Basic Medical Sciences in Oslo.

Certain B vitamins are known to be regulators of Homocysteine and low levels of B-12 and folate have been linked to Alzheimer’s development (1).

In a randomized, controlled trial of B-12/B-6 supplementation vs a placebo, by Professor David Smith of Oxford University, the rate of brain atrophy was 53% lower in the group taking the B vitamins, and this mirrored the decline in homocysteine levels (2).

This study was repeated by de Jager CA and others (3) with B vitamins showing a reduction of 30% in cognitive decline, for those with already mild symptoms over the control group.

B vitamins are made by a healthy gut flora. However as we age, the numbers of commensal (good) bacteria in our gut decline. And so does vitamin B production.

Helga Refsum has highlighted the need for B-12 supplementation, if folate levels are adequate as a preventative aid, in cases especial where mental impairment has already started to take place. 

Other studies, for example by UC Davis Health, have shown links between gut bacteria, plaque formation and inflammatory attack (4).

In a 2015 study involving both David Smith and Helga Refsum, research showed a strong synergystic effect between omega-3 and B vitamins in both reducing homocysteine levels and reducing rates of cognitive decline (5). Where people had low omega-3 levels, B vitamins had no effect; but when omega-3 levels were high, B vitamins reduced cerebral atrophy by 40%.

Homocysteine build up has also been linked to cancer and heart failure.

Prevention strategies are essential for dementia and Alzheimer's, since 'treatment drugs' continue to fail in clinical trials.

In response to yet another such failure 11 top UK doctors wrote an open letter to UK Prime Minister David Cameron, urging him to adopt a colourful Mediterranean diet as the norm in the UK. To quote: "The evidence base for the colourful Mediterranean diet in preventing all of the chronic illnesses plaguing the Western world is overwhelming".