Boosting low vitamin D levels to normal ranges could help protect the brain against a loss of thinking skills as people age, the study authors wrote.
“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 Hypponen, PhD, the senior study author and director of the Australian Centre for Precision Health at the University of South Australia, said in a statement.
“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 said.
Hypponen and colleagues analyzed data for more than 294,000 people in the study ages 37 to 73 in the UK Biobank, looking at the association between vitamin D and the risks of dementia and stroke. About 2,400 people in the study had dementia, while 3,760 had had a stroke.
Vitamin D deficiency was associated with an increased risk of both dementia and stroke, with the strongest associations for those with levels under 25 nanomoles per liter, or nmol/L. In additional analyses that looked at potential causes, low vitamin D levels were associated with dementia but not with the risk of stroke.
The risk of dementia was predicted to be 54% higher for participants with low vitamin D levels of 25 nmol/L, as compared with those who had 50 nmol/L, which is considered a normal vitamin D level.
The research team estimated that 17% of dementia cases could potentially be prevented by increasing vitamin D levels from 25 nmol/L to 50 nmol/L.
“In some contexts, where vitamin D deficiency is relatively common, our findings have important implications for dementia risks,” Hypponen said. “Indeed, in this UK population, we observed that up to 17 percent of dementia cases might have been avoided by boosting vitamin D levels to be within a normal range.”
Dementia is a chronic syndrome that leads to a decline in thinking skills, including memory loss and having a hard time with daily activities. Nearly 6 million Americans over age 65 live with Alzheimer’s disease, which is the most common form of dementia, according to the latest CDC estimate. That is expected to grow to 14 million people by 2060, the CDC said.
More research is needed to confirm the link between low vitamin D levels and the risk of dementia, the study authors wrote. Although an association was found, that doesn’t confirm causation.
Vitamin D levels can be increased through sun exposure, nutrition, and supplements.
“Dementia is a progressive and debilitating disease that can devastate individuals and families alike,” Hypponen said. “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.”