Vitamin D Linked to Lower Tau

A new study published in Neurology Open Access on April 1, 2026, suggests that higher levels of Vitamin D in midlife are associated with lower levels of tau protein in the brain years later. Tau protein is a key biomarker for Alzheimer s disease. The research, led by Martin David Mulligan of the University of Galway, followed 793 adults for an average of 16 years, measuring their Vitamin D levels at the start and later assessing tau and amyloid beta proteins via brain scans. While a link was found between Vitamin D and tau, no association was observed with amyloid beta. The study, supported by the United States — National Institutes of Health, United States — National Institute of Neurological Disorders and Stroke, Republic of Ireland — Irish Research Council, and New Zealand — Health Research Council, emphasizes that it shows an association, not direct causation, and calls for further research, particularly clinical trials, to confirm if modifying Vitamin D levels can directly reduce dementia risk. The findings highlight midlife as a crucial period for brain health interventions.