Taking Vitamin D Could Help Prevent Dementia

Taking vitamin D supplements may help prevent dementia, according to a new study published in Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring.  

Researchers from the University of Calgary’s Hotchkiss Brain Institute in Canada and the University of Exeter in the UK looked at the relationship between vitamin D supplementation and dementia in more than 12,388 participants of the US National Alzheimer's Coordinating Center, who had a mean age of 71 and were dementia-free when they signed up.

The large scale found that taking vitamin D was associated with living dementia-free for longer and that there were 40% fewer dementia diagnoses in the group who took supplements. Across the entire sample, 2,696 participants progressed to dementia over ten years, and among them, 2,017 (75 percent) had no exposure to vitamin D throughout all visits prior to dementia diagnosis, and 679 (25 percent) had baseline exposure.

“We know that vitamin D has some effects on the brain that could have implications for reducing dementia, however, so far, research has yielded conflicting results, “said study leader Zahinoor Ismail, MD.  “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.”  

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While vitamin D was effective across the board, 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.

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 authors suggest that people who carry the APOEe4 gene absorb vitamin D better from their intestines, which might reduce the vitamin D supplementation effect. However, no blood levels were drawn to test this hypothesis.

Co-author Byron Creese, MD said,, “Preventing dementia or even delaying its onset is vitally important given the growing numbers of people affected. The link with vitamin D in this study suggests that taking vitamin D supplements may be beneficial in preventing or delaying dementia, but we now need clinical trials to confirm whether this is really the case.”

The study, ‘Sex, Cognitive Status, and APOE Effects for Vitamin D Exposure and Incident Dementia,’ adds to previous research that found low levels of vitamin D to be linked to higher dementia risk. Vitamin D is involved in the clearance of amyloid in the brain, the accumulation of which is one of the hallmarks of Alzheimer’s disease. Studies have also found that vitamin D may help protect the brain against the buildup of tau, another protein involved in the development of dementia.