It is thought that the vitamin helps clear the brain of the characteristic tangles of proteins that form in dementia.
Taking vitamin D supplement could decrease dementia risk, a large study suggests.
People who took vitamin D supplements lived for longer without developing dementia and overall had a 40 percent lower risk of developing the disease.
Adequate vitamin D levels have been repeatedly linked to lower dementia risk by research (1, 2, 3, 4).
One study has even suggested that adequate levels of vitamin D could prevent almost one-in-five cases of dementia (Navale et al., 2022).
However, the link remains somewhat controversial, with other studies finding no connection (also: Owusu et al., 2018).
Professor Zahinoor Ismail, the study’s first author, acknowledged the contradictory findings from past studies:
“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.”
Vitamin D and dementia
For this study, data from over 12,000 participants in the US National Alzheimer’s Coordinating Center was analysed.
Just over one-third were taking vitamin D supplements.
The results showed that vitamin D supplementation was associated with a reduced dementia risk in all groups.
However, the connection was stronger in women and people who had no pre-existing cognitive deficits, such as mild cognitive impairment.
Similarly, carriers of the APOEe4 gene appeared to benefit more from vitamin D supplementation.
The APOEe4 gene significantly increases the risk of developing dementia.
It is thought that vitamin D helps to clear the brain of the characteristic tangles of proteins that form, known as amyloid and tau.
Dr Byron Creese, study co-author, 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 ongoing VitaMIND study at the University of Exeter is exploring this issue further by randomly assigning participants to either take vitamin D or placebo and examining changes in memory and thinking tests over time.”
Despite these findings, it is not recommended to take high levels of vitamin D as a preventative measure.
Recommended doses are 600 IU per day for people under 70 and 800 IU for those over 70.
The study was published in the journal Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring (Ghahremani et al., 2023).
