A recent study of nearly 300,000 people discovered a link between vitamin D deficiency and the risk of dementia. Within days, dozens of articles lauded the vitamin as a dementia preventer. But wait: Here’s why you shouldn’t rush to the vitamins and supplements section.
Dementia, which affects thinking and behavior as you age, is one of the leading causes of disability and dependency among older people worldwide. But what if you could halt the progression of this degenerative disease?
A groundbreaking study from the University of South Australia may make this a reality, as new genetic research reveals a direct link between dementia and a lack of vitamin D.
Vitamin D is a hormone precursor that is increasingly recognized for widespread effects, including on brain health. However, it has been very difficult to examine what would happen if we were able to prevent vitamin D deficiency.
Prof Hyppönen
Investigating the association between vitamin D, neuroimaging features, and the risk of dementia and stroke, the study found:
- low levels of vitamin D were associated with lower brain volumes and an increased risk of dementia and stroke
- genetic analyses supported a causal effect of vitamin D deficiency and dementia.
- in some populations, as much as 17 percent of dementia cases might be prevented by increasing everyone to normal levels of vitamin D (50 nmol/L).
Dementia is a chronic or progressive syndrome that causes a cognitive function to deteriorate. Dementia affects approximately 487,500 Australians and is the country’s second leading cause of death. More than 55 million people worldwide have dementia, with 10 million new cases diagnosed each year.
The genetic study, funded by the National Health and Medical Research Council, examined the impact of low vitamin D (25 nmol/L) levels on the risk of dementia and stroke in 294,514 participants from the UK Biobank. Nonlinear Mendelian randomization (MR) was used to test for underlying causality for neuroimaging outcomes, dementia, and stroke. MR is a method of using measured variation in genes to examine the causal effect of a modifiable exposure on disease.
Senior investigator and Director of UniSA’s Australian Centre for Precision Health, Professor Elina Hyppönen, says the findings are important for the prevention of dementia and appreciating the need to abolish vitamin D deficiency.
“Vitamin D is a hormone precursor that is increasingly recognized for widespread effects, including on brain health,” Prof Hyppönen says. “However, it has been very difficult to examine what would happen if we were able to prevent vitamin D deficiency.”
“Our study is the first to use robust genetic analyses on a large population to examine the effect of very low levels of vitamin D on the risks of dementia and stroke. Our findings have important implications for dementia risk in some contexts where vitamin D deficiency is relatively common. Indeed, in this UK population, we discovered that increasing vitamin D levels to a normal range could have prevented up to 17% of dementia cases.”
The findings are incredibly significant given the high prevalence of dementia around the world.
“Dementia is a progressive and debilitating disease that can devastate individuals and families alike,” Prof Hyppönen says.
“If we can change this reality by ensuring that none of us are severely vitamin D deficient, it will have additional benefits and could improve the health and well-being of thousands. Most of us should be fine, but for anyone who does not get enough vitamin D from the sun for whatever reason, dietary changes may not be enough, and supplementation may be necessary.”
Furthermore, clinical trials have been conducted to see if the vitamin can reduce the risk of developing Alzheimer’s or other dementias. Two systematic reviews that compiled all of these clinical trials together found insufficient evidence to show that vitamin D has any protective effect against dementia.
