Vitamin D reduced dementia by 40%

Vitamin D supplementation and incident dementia: Effects of sex, APOE, and baseline cognitive status

Alberta, Canada Known association, vitamin D deficiency, incident dementia

Role of supplementation is unclear. Prospectively study Associations, vitamin D supplementation and incident dementia N = 12,388 dementia-free people (from the National Alzheimer’s Coordinating Center)


Baseline exposure to vitamin D was considered D+

No exposure prior to dementia onset was considered D−

MCI and depression were both more frequent in the D− group, compared to D+

People taking vitamin D had less MCI and less depression

Adjusted for age, sex, education, race, cognitive diagnosis, depression, and apolipoprotein E (APOE) ε4. 

Potential interactions between exposure and model covariates were explored.


Across all formulations, 

vitamin D exposure was associated with significantly longer dementia-free survival,

and lower dementia incidence rate than no exposure

Hazard ratio = 0.60

(95% confidence interval: 


Vitamin D exposure was associated with 40% lower dementia incidence versus no exposure.

Over 10 year follow up of 


2,696 participants progressed to dementia

Among them the 2,696

2,017 (74.8%) had no exposure to vitamin D

679 (25.2%) had baseline exposure

Exposure to vitamin D was associated with significantly higher dementia-free survival

5-year survival for D− was 68.4%

5-year survival for D+ was 83.6%

The effect of vitamin D on incidence rate differed significantly,

Vitamin D effects were significantly greater in females versus males

Vitamin D effects were significantly greater in normal cognition versus mild cognitive impairment.

Vitamin D effects were significantly greater in apolipoprotein E ε4 non-carriers versus carriers.

Vitamin D effects were less significantly apolipoprotein E ε4 carriers. (25% one copy, 3% two copies)

Vitamin D has potential for dementia prevention, especially in the high-risk strata.

Vitamin D deficiency, worldwide prevalence of up to 1 billion.

Mechanism of action…

Vitamin D is known to participate in the clearance of amyloid beta (Aβ) aggregates,

one of the hallmarks of Alzheimer’s disease (AD), 

and may provide neuroprotection against Aβ-induced tau hyperphosphorylation

(neurofibrillary tangles)

Cholecalciferol may be more effective than ergocalciferol


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