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  • Over 55 million people globally live with dementia, with researchers estimating that number to grow to 78 million by 2030.
  • Researchers from the University of South Australia uncovered evidence linking vitamin D deficiency to an increased risk for dementia and stroke.
  • Scientists agree more research is required to fully understand the link between vitamin D and heightened dementia risk.

Vitamin D has long been touted as an important part of a person’s health. Not only is it crucial for bone health, but past research shows vitamin D also plays an important role in immune system function.

Additionally, vitamin D deficiency has been linked to diabetes, cardiovascular disease, and respiratory diseases like acute respiratory distress syndrome (ARDS).

Adding to this list, researchers from the University of South Australia believe they have evidence linking vitamin D deficiency to an increased risk for dementia and stroke.

The study was recently published in The American Journal of Clinical Nutrition.

The term “dementia” refers to a collection of diseases that affect a person’s cognitive abilities. Dementia affects people’s ability to think, remember, and communicate normally.

Over 55 million people globally live with dementia. Researchers believe that number will grow to 78 million by 2030.

The most common type of dementia is Alzheimer’s disease, accounting for 60% to 70% of dementia cases.

Other types of dementia include:

In addition to vascular dementia caused by stroke, past research shows stroke patients have an increased risk of developing dementia.

Researchers analyzed genetic data from almost 295,000 participants in the UK Biobank biomedical database for this study. Scientists measured variations in participants’ genes to find how a low vitamin D level impacted a person’s neuroimaging of the brain and their risk for dementia and stroke.

Researchers associated a lower vitamin D level with a lower brain volume and an increased risk of dementia and stroke. They also stated their genetic analysis supports vitamin D deficiency’s causal effect on dementia.

According to Prof. Elina Hyppönen, senior investigator and director of the Australian Centre for Precision Health at the University of South Australia, researchers have long suspected that vitamin D may have implications for the development of neurocognitive diseases such as dementia. However, evidence about whether these effects are causal has been lacking.

“Indeed, it has been very difficult to prove the effects of vitamin D on brain health or other diseases, in large part as clinical trials in people who are clinically vitamin D deficient would not be ethical to conduct,” Prof. Hyppönen told Medical News Today.

“Therefore, using a novel genetic design, we wanted to see whether we can provide causal evidence for a role of vitamin D in brain health, and specifically, to see whether improvements in vitamin D status among people who are vitamin D deficient will help,” she explained.

Previous research — including a study in 2018 that conducted a systematic review and analysis of over 70 clinical and pre-clinical studies about the role of vitamin D in neurodegenerative diseases like Alzheimer’s and Parkinson’s disease — concluded there was no concrete evidence that vitamin D was neuroprotective.

However, more recent research supports vitamin D’s role may play in dementia prevention.

When asked how this research might help with dementia and stroke prevention in the future, Hyppönen said this research highlights the importance of preventing and avoiding vitamin D deficiency.

“This is likely to be helpful not only for dementia risk but also for overall health,” she added. “In my opinion, strategies for food fortification with vitamin D should be given serious thought, and in countries where this has already been done, it has been possible to lift the concentrations at the population level.”

And Hyppönen said she is already planning the next steps for this research.

It is important to work further to establish which of the proposed health effects of vitamin D are truly causal and whether the thresholds for serum concentrations that are supported by our work so far also apply for other health outcomes,” she explained.

Dr. Heather Snyder, vice president of medical and scientific relations for the Alzheimer’s Association, is also interested in seeing the next research steps for these findings.

“This is an interesting study exploring the link between vitamin D deficiency and dementia risk, and adds an interesting additional link suggesting there may be a genetic component that gives more information about this relationship,” she told MNT. “That being said, more research is needed, including intervention studies to determine if stabilizing vitamin D levels would have a benefit on dementia risk reduction.”

“All this to say, the body and brain are closely connected and it’s important to take care of your overall health and well-being — including vitamin levels,” Snyder added. “Talk to your doctor if you have any concerns regarding your health, including any memory concerns.”