People with low levels of vitamin D have a 53% risk of developing dementia compared with those who have normal levels of vitamin D.
Older patients with very low levels of vitamin D have a nearly doubled risk for dementia compared with people who have higher levels of vitamin D, according to the largest study of its kind to date. Results of the study were published August 6, 2014, online in Neurology.
The study examined blood levels of vitamin D, which includes vitamin D from food, supplements, and exposure to sun. A total of 1,658 people over age 65 who were dementia free had their blood levels of vitamin D tested. The investigators adjusted for other factors that could affect dementia risk.
After an average of 6 years, 171 developed dementia and 102 had Alzheimer’s disease. The researchers found people with low levels of vitamin D had a 53% increased risk of developing dementia, and those who were severely deficient had a 125% increased risk of developing dementia compared with those who had normal levels of vitamin D.
People with lower levels of vitamin D were nearly 70% more likely to develop Alzheimer’s disease and those with severe deficiency were over 120% more likely to develop the disease.
Author David J. Llewellyn, PhD, of the University of Exeter Medical School in the United Kingdom said the investigators expected to see an association between low vitamin D levels and the risk of dementia and Alzheimer’s disease, but the results were surprising given that they found it to be twice as strong as anticipated.
He said that clinical trials are now needed to establish whether eating foods such as oily fish or taking vitamin D supplements can delay or 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,” he said in a statement. “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.”