Low blood levels of vitamin D may increase the risk of dementia and Alzheimer’s disease, says a new hypothesis based on existing risk factors.
A growing number of studies have linked deficiency of vitamin D to increased risks of cardiovascular diseases, diabetes, osteoporosis, depression, and periodontal disease, all of which have been linked to some degree to increased risks for dementia.
Based on these risk factors, William Grant, PhD, from the Sunlight, Nutrition, and Health Research Center (SUNARC) hypothesizes that vitamin D deficiency may also be a risk factor for dementia. The hypothesis is published in the current issue of the Journal of Alzheimer's Disease.
"There are established criteria for causality in a biological system,” explained Grant. “The important criteria include strength of association, consistency of findings, determination of the dose-response relation, an understanding of the mechanisms, and experimental verification.
“To date, the evidence includes observational studies supporting a beneficial role of vitamin D in reducing the risk of diseases linked to dementia such as vascular and metabolic diseases, as well as an understanding of the role of vitamin D in reducing the risk of several mechanisms that lead to dementia."
A recent study from China, reported that as many as 90 per cent of 50 to 70 year olds may be vitamin D deficient or insufficient, with similar findings being reported in Western populations.
Alzheimer's disease is the most common form of dementia and currently affects over 13 million people worldwide. The direct and indirect cost of Alzheimer care is over $100 bn (€ 81 bn) in the US, while direct costs in the UK are estimated at £15 bn (€ 22 bn).
Source: Journal of Alzheimer's Disease May 2009, 17:1, http://www.j-alz.com/issues/17/vol17-1.html "Does Vitamin D Reduce the Risk of Dementia?" Author: W.B. Grant