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# Vitamin B12 deficiency linked to dementia risk
- URL: https://www.foodconsumer.org/vitamin_b12_deficiency_dementia_0820120929/
- Published: 2012-08-20T22:28:00.000Z
- Updated: 2026-09-22T15:55:26.000Z
- Description: A review of 43 studies in International Psychogeriatrics tied low-normal or deficient vitamin B12 to higher risk of Alzheimer's, vascular dementia, Parkinson's and cognitive impairment, but found supplements did not help people with dementia who were not deficient.
- Author: Food Consumer
- Tags: Vitamins, Nutrition, #vivvo-import

By David Liu, PHD

Monday Aug 20, 2012 (foodconsumer.org) -- A review study in the Jan 2012 issue of International Psychogeriatrics sugggests that taking vitamin B12 can help vitamin B12 deficiency and prevent dementia or improve cognitive impairment due to the nutrition deficiency.

The review intended to examine the associations between low vitamin B12 levels, neurodegenerative disease and cognintive impairment also found that supplementation of vitamin b12 does not help dementia people without preexisting vitamin b12 deficiency.

E. Moore of The University of Melbourne in Victoria, Australia and colleagues reviewed 43 studies investigating the assocation of vitamin b12 and cognitive impairment or dementia and 17 studies reported on the efficacy of vitamin b12 therapy for these conditions.

The researchers found that vitamin b12 levels in the subclinical low-normal range (<250 ρmol/L) or vitamin B12 deficiency are associated with increased risk for Alzheimer;s disease, vascular dementia and Parkinson's disease and cognitive impairment.

Vegetarian diet and metformin use lower vitamin b12 levels and they act as independent risk factors for cognitive impairment or dementia.

Vitamin B12 supplements administered orally or parenterally at high dose (1 mg daily) were found effective in treating vitamin b12 deficiency, but improved cognition only in people with pre-existing vitamin B12 deficiency.

The researchers concluded "Low serum vitamin B12 levels are associated with neurodegenerative disease and cognitive impairment, dementia, Alzheimer's disease and Parkinson's disease."

They also found "There is a small subset of dementias that are reversible with vitamin B12 therapy and this treatment is inexpensive and safe."

Howver, vitamin B12 therapy does not improve cognition in those without pre-existing deficiency.