Vitamin D in your 30s and 40s affects your brain decades later
16-year study. ~800 people. Higher Vitamin D levels in midlife → lower tau protein levels later. Tau buildup is associated with Alzheimer’s and other forms of cognitive decline.
The implication is that the decisions you make in your 30s and 40s are already shaping what your brain looks like at 60 and 70.
Vitamin D is cheap. Sunlight is free. The study design isn’t perfect but it’s hard to argue against checking your levels.