Vitamin D supplements may help prevent dementia: Study

TORONTO: Taking vitamin D supplements may help ward off dementia, according to a study led by an international team of researchers.

Researchers at the University of Calgary's Hotchkiss Brain Institute in Canada and the University of Exeter in the UK explored the relationship between vitamin D supplementation and dementia in more than 12,388 participants. Of the group, 37 per cent (4,637) took vitamin D supplements.

The team found that taking vitamin D was associated with living dementia-free for longer, and they also found 40 per cent fewer dementia diagnoses in the group who took supplements.

Across the entire sample, 2,696 participants progressed to dementia over ten years; amongst them, 2,017 (75 per cent) had no exposure to vitamin D throughout all visits prior to dementia diagnosis, and 679 (25 per cent) had baseline exposure.

"We know that vitamin D has some effects in the brain that could have implications for reducing dementia, however so far, research has yielded conflicting results. Our findings give key insights into groups who might be specifically targeted for vitamin D supplementation. Overall, we found evidence to suggest that earlier supplementation might be particularly beneficial, before the onset of cognitive decline," said lead researcher Professor Zahinoor Ismail.

The findings are published in the journal Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring,

While Vitamin D was effective in all groups, the team found that effects were significantly greater in females, compared to males. Similarly, effects were greater in people with normal cognition, compared to those who reported signs of mild cognitive impairment -- changes to cognition which have been linked to a higher risk of dementia.

The effects of vitamin D were also significantly greater in people who did not carry the APOEe4 gene, known to present a higher risk for Alzheimer's dementia, compared to non-carriers. The study suggests that people who carry the APOEe4 gene absorb vitamin D better from their intestine, which might reduce the vitamin D supplementation effect. However, no blood levels were drawn to test this hypothesis.