When researchers from the University of Exeter Medical School set out to see how much impact vitamin D levels had on dementia, they got more than they bargained for.
"We expected to find an association between low vitamin D levels and the risk of dementia and Alzheimer's disease, but the results were surprising - we actually found that the association was twice as strong as we anticipated," lead researcher David Llewellyn said in a report.
Early signs of a link The Exeter study wasn't the first to suggest that vitamin D may have a benefit in Alzheimer's care. According to the Alzheimer's Drug Discovery Foundation, several animal and observational studies have shown that the nutrient might at least be linked to the health condition. The foundation said that increasing vitamin D intake could help prevent the disease, but research to that point had been inconclusive. Exeter researchers also said that previous studies had shown that low levels of the vitamin could make general cognitive impairment more likely, but whether that also increased dementia risk was unknown.
Vitamin D may protect brain In what researchers said what the largest study of its kind ever conducted, people who had severely low levels of the vitamin were found to have more than twice the risk of developing Alzheimer's disease and dementia as those with normal amounts.
The Exeter study of more than 1,600 people over 65 showed those with severely low levels of vitamin D were 122 percent more likely to develop Alzheimer's over six years and 125 percent more likely to develop dementia. For participants with moderate deficiencies, Alzheimer's was 69 percent more likely and dementia was 53 percent more likely.
Supplementing Vitamin D The three main ways to boost vitamin D levels are spending time in the sun, eating foods such as fish and taking supplements, researchers said. According to Llewellyn, about 15 minutes in the sun on a bright day could be enough to raise vitamin D to healthy levels.
Llewellyn warned that the study didn't prove that vitamin D deficiency caused dementia, but described the findings as encouraging. Further studies will still be needed to determine whether increasing vitamin D intake could delay the onset of dementia or even prevent it, he said.