Study: Vitamin D deficiency may double risk of dementia

Older individuals deficient in vitamin D may have double the risk of dementia and Alzheimer's disease, according to a new study published Wednesday. Researchers found that in individuals aged 65 and older, those with "low levels" of vitamin D had a 53 percent increased risk of developing dementia, while those with a "more significant deficiency had a 125 percent increased risk." Both groups were compared to individuals with normal vitamin D levels.

Additionally, the study found that otherwise healthy individuals with lower levels of vitamin D were nearly 70 percent more likely to develop Alzheimer's disease, while those who had a severe vitamin D deficiency were over 120 percent more likely.

That the correlation was so significant came as a surprise to researchers, said Dr. Iain Lang, one of the authors of the study. "We're quite surprised that the results are so big," Lang told BBC Radio 4. "I don't think this is they key to dementia or anything like that, but it's a really important step in finding out what might be going on there."

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Vitamin D typically comes from sun exposure or a diet involving oily fish and certain dairy products. Supplements are also available, although Lang said the research was unclear as to whether deliberately increased intake could be beneficial. "What we haven't looked at here is whether, for example, supplementation is something that can... either delay or prevent the onset of dementia," he told the BBC. "We're not at that stage yet, but this is indicative that it's probably time to do that research."

Read the rest of the study at the journal Neurology.