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Sunlight is one of the ways to increase vitamin D levels. Westend61/Getty Images
  • Researchers in Australia say vitamin D deficiency may increase the risk of developing dementia.
  • They say boosting low vitamin D levels in people may be a preventative measure against dementia.
  • Experts say more study is needed, but they note that vitamin D has many health benefits with few potential side effects.

Vitamin D deficiency may be associated with an increased risk of dementia.

That’s according to researchers from the University of South Australia who say they have found that a low level of vitamin D is associated with an increased risk of both dementia and stroke.

“Vitamin D is a hormone precursor that is increasingly recognized for widespread effects, including on brain health, but until now it has been very difficult to examine what would happen if we were able to prevent vitamin D deficiency,” Elina Hyppönen, a professor at the university and senior investigator of the study as well as the director of UniSA’s Australian Centre for Precision Health, said in a press release.

“Our study is the first to examine the effect of very low levels of vitamin D on the risks of dementia and stroke, using robust genetic analyses among a large population,” she added.

The researchers used data from more than 294,000 participants in the UK Biobank.

They analyzed how different levels of vitamin D impact dementia risk.

They say their findings suggest there may be an association between low vitamin D and a heightened risk of dementia.

The strongest association was seen in people who had vitamin D levels below 25 nanomoles per liter (nmol/L). In fact, dementia risk was predicted to be 54 percent higher for those with vitamin D levels of 25 nmol/L compared with participants who had normal vitamin D levels (50 nomol/L).

In some of the populations studied, researchers found that up to 17 percent of dementia cases may have been prevented if vitamin D levels were increased to a normal level (50 nmol/L).

Dr. Scott Kaiser is a geriatrician and director of Geriatric Cognitive Health for the Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, California.

He says that while the study showed an association, more research is needed to confirm causation on whether low vitamin D levels do in fact raise the risk of dementia.

“This is a very interesting study and it adds to a very important area of inquiry between vitamin D and dementia risk. But at the end of the day, it’s still an association and kind of fodder for more study needed,” Kaiser told Healthline.

However, if other studies confirm the link between vitamin D deficiency and dementia, Kaiser says that could be useful in lowering the risk of dementia.

“I love that the authors suggest that addressing vitamin D deficiency could be an important strategy, in terms of population-level prevention,” he said. “It’s worth investigating further if it might make sense to identify people who are at high risk, identify people who are vitamin D deficient and focus on providing getting adequate vitamin D levels, whether it’s through more sunlight, through dietary sources or through supplementation in those high risk groups.”

Dementia is an umbrella term for a variety of symptoms, including memory loss and difficulties with cognition that impact daily life.

Alzheimer’s is the most common form of dementia. The Centers for Disease Control and Prevention estimates there are 5.8 million people in the United States living with either Alzheimer’s disease or related dementias.

Dr. Marilyn Tan is a clinical associate professor of medicine in the Endocrinology, Gerontology and Metabolism Department at Stanford University in California.

She says that while more study is needed to determine if vitamin D could have a beneficial effect, vitamin D supplementation is generally considered safe and may have other health benefits.

“The important thing about this study is to remind people to think about getting regular routine health care, getting regular checkups, getting their labs checked,” Tan told Healthline. “And if your vitamin D levels are low, certainly there are benefits to supplementing to bring your levels up into normal range, particularly for your bone health, and may there be an extra benefit for reducing the risk of dementia? Potentially. But I think it’s too hard to say because we don’t have a trial that gave an intervention of vitamin D supplementation to show an improvement in dementia risk.”

“Doing these activities is unlikely to cause harm. And that’s the thing with vitamin D that’s nice, and I think that’s why there’s so much interest. The intervention may or may not be a game-changer in terms of changing your outcomes, but it’s unlikely to hurt,” she added.