DrG's Medisense Feature Article

Errata For March 2025 Issue
By Ann Gerhardt, MD
May 2025
Print Version

About Vitamin D3, I said previously that it has nothing to do with brain or dementia.  I found with further research that Vitamin D (cholecalciferol)  does cross the blood-brain barrier and binds to abundant vitamin D receptors (VDRs) on neurons, and is  converted to the active form, 1,25 di(OH)D.  Activated vitamin D  has a role in enabling synthesis of neurochemicals which determine function  and protection against damage.  It may also reduce accumulation of beta-amyloid (a cause of dementia) by enhancing its breakdown.

D deficiency, with levels less than 25 nmol/L and  genetic mutations of the VDR are associated with β-amyloid accumulation and increased risk of cognitive impairment.  In mouse models of Alzheimer’s, supplements of the active form of vitamin D increased the process of  removing beta amyloid from brain.  Vitamin D supplements in deficient individuals reduce risk of senility, but only one study of a small number of Alzheimer’s patients showed cognitive improvement with any D supplement.   So, in the absence of dementia and known D deficiency, it seems logical that a D supplement might be prudent.