The supplements vitamin D may help prevent dementia proactively, according to a new major British-Canadian scientific study. The protective effect appears to be significantly greater in women than in men, as well as in those with normal cognitive function compared to those who have begun to show signs of mild cognitive impairment, usually a precursor to dementia.

The researchers from the universities of Calgary (Canada) and Exeter (UK), led by Professor Zahinur Ismail, who made the relevant publication in the Alzheimer’s journal “Alzheimer’s & Dementia: Assessment, Diagnosis and Monitoring”, analyzed over a decade data on almost 12,400 people with an average age of 71 years. Of these, 37% were taking extra vitamin D supplements.

Over the course of a decade, nearly 2,700 people were diagnosed with some form of dementia such as Alzheimer’s disease. It was found that in the group of those taking such supplements, there were 40% fewer dementia diagnoses, while these people lived dementia-free longer on average.

“We know that vitamin D has some effects on the brain that could reduce dementia, but until now the relevant research has provided conflicting results. Overall, we found evidence to suggest that earlier vitamin D supplementation may be particularly beneficial, before the manifestation of cognitive impairment,” said the lead researcher.

The preventive effect of vitamin D is significantly greater in people who are not carriers of the APOE4 gene, which preeminently increases the genetic predisposition to Alzheimer’s.

Previous studies have also found that low levels of D are associated with a higher risk of dementia. The vitamin in question is involved in ridding the brain of the beta amyloid protein, the toxic accumulation of which is a hallmark of Alzheimer’s disease. There is also other evidence from research that D may protect the brain from another potentially toxic protein, tau, which is involved in causing dementia.

Researcher Dr Byron Cries of Exeter said: “Preventing dementia or even delaying its onset is vitally important given the increasing number of people affected by it. The link with vitamin D emerging from our new study , suggests that vitamin D supplementation may be beneficial in preventing or delaying dementia. But clinical trials are now needed to confirm whether this is indeed the case.”