One Common Vitamin Could Lower Toxic Alzheimer's Proteins, Research Suggests - ScienceAlert

What the report says

ScienceAlert reported on July 30, 2026, that a study in Neurology Open Access has linked adequate vitamin D levels in midlife with lower later-life deposits of tau, a protein associated with Alzheimer’s disease. The article says the research addresses a gap in earlier work, which had mostly connected low vitamin D in adults over 70 with higher dementia risk rather than examining brain changes beginning in midlife.

The study analyzed 793 dementia-free participants from the US-based Framingham Heart Study. Their blood vitamin D levels were measured when they were about 39 years old on average. Roughly 16 years later, about 430 participants underwent PET brain scans to look for tau and amyloid beta, two proteins commonly studied as Alzheimer’s biomarkers. Researchers found that higher vitamin D levels at the earlier measurement were associated with lower tau deposits later, while no similar link was seen for amyloid beta.

Emer McGrath, a neurologist at the University of Galway and senior author of the study, told ScienceAlert the findings suggest vitamin D in midlife may be relevant to future brain health. However, the study was observational, meaning it cannot prove that vitamin D directly prevented tau buildup or reduced dementia risk.

The report also noted that earlier supplementation research in older adults with memory complaints did not show an effect on tau over one year. The researchers suggested future clinical trials would be needed to test whether vitamin D supplements, higher doses, longer treatment periods or earlier intervention in cognitively healthy adults could make a measurable difference.