The largest study of its kind concluded older individuals who do not get enough vitamin D could have double the risk of developing Alzheimer's or dementia.
The study, published in the Aug. 6 online edition of Neurology, looked at blood vitamin levels in older adults, the American Academy of Neurology (AAN) reported.
"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," said study author David J. Llewellyn, PhD, of the University of Exeter Medical School in the United Kingdom.
The researchers looked at the blood of 1,658 people over the age of 65 who did not have dementia. After about six years 171 of the participants developed dementia and 171 had Alzheimer's. The team found people with low vitamin D levels had a 53 percent increased risk of developing dementia; those who were severely deficient had a 125-percent increased risk of developing the conditions when compared with normal study participants. People with low levels of the vitamin were also 70 percent more likely to develop Alzheimer's; 120 percent more likely if severely deficient.
The results remained consistent even after researchers adjusted for other risk factors such as smoking and alcohol consumption.
"Clinical trials are now needed to establish whether eating foods such as oily fish or taking vitamin D supplements can delay or even prevent the onset of Alzheimer's disease and dementia. We need to be cautious at this early stage and our latest results do not demonstrate that low vitamin D levels cause dementia. That said, our findings are very encouraging, and even if a small number of people could benefit, this would have enormous public health implications given the devastating and costly nature of dementia," Llewellyn said.
