There is some evidence to suggest that taking vitamin D supplements may have a protective effect against dementia, but the research is still ongoing and more studies are needed to confirm this potential link. Several observational studies have found an association between low levels of vitamin D and an increased risk of dementia, including Alzheimer’s disease. However, it’s important to note that these types of studies cannot establish causality.
According to a new large-scale study, taking vitamin D supplements may help prevent dementia. Researchers from the University of Calgary’s Hotchkiss Brain Institute in Canada and the University of Exeter in the United Kingdom investigated the link between vitamin D supplementation and dementia in over 12,388 participants of the US National Alzheimer’s Coordinating Center, who were 71 years old on average and dementia-free when they signed up. 37 percent (4,637) of the participants took vitamin D supplements.
The study, published in Alzheimer’s & Dementia: Diagnosis, Assessment, and Disease Monitoring, discovered that taking vitamin D supplements was associated with living dementia-free for longer periods of time, as well as 40% fewer dementia diagnoses in the supplement group.
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.
Professor Zahinoor Ismail
Over the course of ten years, 2,696 participants developed dementia; of these, 2,017 (75%) had no exposure to vitamin D during all visits prior to dementia diagnosis, while 679 (25%) had baseline exposure.
Professor Zahinoor Ismail, of the University of Calgary and the University of Exeter, who led the research, said: “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. Our findings give key insights into groups that 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.”
While vitamin D was effective in all groups, the team discovered that females had significantly greater effects than males. Similarly, effects were greater in people with normal cognition versus those with mild cognitive impairment – changes in cognition that have been linked to an increased risk of dementia.
When compared to non-carriers, the effects of vitamin D were also significantly greater in people who did not carry the APOEe4 gene, which has been linked to an increased risk of Alzheimer’s disease. According to the authors, people who have the APOEe4 gene absorb vitamin D better from their intestines, which may reduce the effect of vitamin D supplementation. However, no blood samples were taken to test this theory.
Previous research has found that low levels of vitamin D are 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 provide help to protect the brain against the build-up of tau, another protein involved in the development of dementia.
Dr. Byron Creese of the University of Exeter, a co-author, stated: “Given the growing number of people affected by dementia, preventing or even delaying its onset is critical. The link with vitamin D in this study suggests that taking vitamin D supplements may be beneficial in preventing or delaying dementia, but clinical trials are needed to confirm this. The ongoing VitaMIND study at the University of Exeter is delving deeper into this issue by randomly assigning participants to either vitamin D or a placebo and examining changes in memory and thinking tests over time.”
