Vitamin D-efense: Getting more sun could help protect against dementia and strokes

ADELAIDE, Australia — More sunshine could help ward off dementia, according to a new study which reveals a direct link between vitamin D deficiency and cognitive decline.

The world-first study discovered that cases of dementia could drop by nearly a fifth if people who are deficient in vitamin D take more supplements to bring them up to healthy levels. Pills aren’t the only solution though, as the skin makes the “sunshine vitamin” after exposure to UV light.

A team from the University of South Australia looked at nearly 300,000 people from the UK Biobank, examining the impact of low levels of vitamin D and the risk of dementia and stroke. They found that low levels of vitamin D displayed a link to lower brain volumes and an increased risk of both conditions.

Further genetic analyses supported a causal effect of vitamin D deficiency and dementia. Researchers report that, in some populations, as much as 17 percent of dementia cases might be preventable through higher vitamin D intake.

Dementia is one of the major causes of disability and dependency among older people worldwide, affecting thinking and behaviors as patients age. Globally, more than 55 million people have dementia, with 10 million new cases diagnosed every year. Dementia cases worldwide will triple to more than 150 million by 2050, according to estimates.

Vitamin D has a major impact on the brain

Study author Professor Elina Hyppönen, senior investigator and director of UniSA’s Australian Centre for Precision Health, says the findings are important for the prevention of dementia and appreciating the need to battle vitamin D deficiency.

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,” Prof. Hyppönen says in a university 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.

“In some contexts, where vitamin D deficiency is relatively common, our findings have important implications for dementia risks. Indeed, in this UK population we observed that up to 17 per cent of dementia cases might have been avoided by boosting vitamin D levels to be within a normal range.”

The genetic study analyzed data from 294,514 participants from the UK Biobank, examining the impact of low levels of vitamin D (25 nmol/L) and the risk of dementia and stroke.

Nonlinear Mendelian randomization (MR) – a method of using measured variation in genes to examine the causal effect of a modifiable exposure on disease – helped researchers test for underlying causality for neuroimaging outcomes, dementia, and stroke.

Dementia is a progressive and debilitating disease that can devastate individuals and families alike,” Prof. Hyppönen says.

“If we’re able to change this reality through ensuring that none of us is severely vitamin D deficient, it would also have further benefits and we could change the health and wellbeing for thousands.”

“Most of us are likely to be ok, but for anyone who for whatever reason may not receive enough vitamin D from the sun, modifications to diet may not be enough, and supplementation may well be needed.”

The study is published in the American Journal of Clinical Nutrition.

South West News Service writer Jim Leffman contributed to this report.

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