People with higher vitamin D levels in their late 30s had significantly less of a key Alzheimer’s protein in their brains 16 years later, according to new research.
The findings, published in Neurology Open Access, suggest that keeping vitamin D topped up in midlife could be a simple way to reduce dementia risk.
That’s because they linked higher blood levels of vitamin D to lower deposits of tau protein in the brain – a recognised biomarker for Alzheimer’s disease.
“Previous research has suggested that Vitamin D may work by reducing inflammation, or by improving antioxidant defences and cell signalling, which may keep the tau protein from accumulating,” lead author Dr Martin Mulligan of the University of Galway told BBC Science Focus.
No link was found with amyloid plaques, the other hallmark of Alzheimer’s. The researchers, however, explained that this may simply reflect the fact that tau accumulates earlier in the disease process, making it easier to detect in younger people.
Vitamin D is produced by your body when your skin is exposed to sunlight, and is also found in foods such as oily fish and eggs.
Nearly 800 dementia-free participants, with an average age of 39, had their vitamin D measured at the start of the study. Their brains were then scanned using PET imaging an average of 16 years later.
Even after accounting for age, sex, cardiovascular risk factors and depression, the association between higher vitamin D and lower tau levels held firm.
Around a third of participants had low vitamin D levels – broadly consistent with global figures, according to Mulligan.
The study is observational, meaning it can’t prove cause and effect. Vitamin D was only measured once, and the cohort was predominantly white, limiting how broadly the findings can be generalised.
Mulligan stressed that the results will need validation in other cohorts before clinical guidance can change.
“We cannot formally advise taking supplements to prevent dementia based solely on these findings, as this hypothesis requires further testing in clinical trials,” he said.
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