A new analysis from the landmark Framingham Heart Study has identified a potential protective association between higher vitamin D levels in midlife and reduced tau accumulation in brain regions most vulnerable to Alzheimer’s disease. Researchers tracked 793 cognitively normal adults over 16 years, measuring vitamin D levels between 2002–2005 and conducting brain PET imaging a decade later. The findings revealed that elevated circulating vitamin D was associated with significantly lower tau pathology in the entorhinal cortex and parahippocampal gyrus, the brain regions where Alzheimer’s pathology characteristically begins. Notably, the relationship was continuous and dose-dependent across the full range of measured vitamin D levels, with no discrete threshold identified. However, the association was specific to tau protein and did not extend to amyloid-beta plaques, the other hallmark Alzheimer’s pathology marker. While these findings are compelling, experts emphasize that the study’s observational design cannot establish causation, and controlled supplementation trials remain essential before clinical recommendations can be made.
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