Vitamin B12
Research reviewed: Up until 03/2026
Vitamin B12 is a dietary supplement with 6 published peer-reviewed studies involving 637 participants, researched for Cognitive Health, Cognitive Function, Neurological Health.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Cognitive Health
StrongCognitive Function
ModerateNeurological Health
WeakResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
Cognitive Health
To evaluate the combined action of folic acid and vitamin B12 supplementation on cognitive performance and inflammation in patients with Alzheimer's disease.
Study Type
Randomized, single-blind, placebo-controlled trial
Purpose
To evaluate the combined action of folic acid and vitamin B12 supplementation on cognitive performance and inflammation in patients with Alzheimer's disease.
Dose
1.2 mg/d folic acid + vitamin B12 50 μg/d or placebo
Participants
120 patients with Alzheimer's Disease and in stable condition (101 completed)
Duration
6 months
Results
Researchers observed that folic acid plus vitamin B12 supplementation significantly improved several aspects of cognitive function compared to controls, including MoCA scores (a test of overall thinking and memory ability), naming ability, orientation (awareness of time and place; P = 0.004), and attention measured. The supplementation also significantly increased SAM (S-adenosylmethionine - a compound important for brain function and cell repair) and the SAM/SAH ratio (a marker of healthy cell processes), while significantly decreasing homocysteine (a harmful amino acid linked to heart and brain problems), SAH (a compound that builds up when cell processes are impaired), and TNFα (a marker of inflammation in the body). Overall, this suggests the vitamins may help improve brain function while also supporting healthier metabolism and reducing inflammation.
To determine whether supplementation with folic acid and vitamin B12, alone and in combination improves cognitive performance
Study Type
Single-blind Experimental Design
Purpose
To determine whether supplementation with folic acid and vitamin B12, alone and in combination improves cognitive performance
Dose
800 µg/day folic acid alone (2 x 400 µg tablets) or 25 µg/day vitamin B12 alone (1 x 25 µg tablet) or 400 µg/day folic acid +25 µg/day vitamin B12, or control (no treatment).
Participants
240 participants with mild cognitive impairment
Duration
6 months
Results
Researchers observed that the group taking folic acid plus vitamin B12 showed significant improvements compared to the control group in several blood markers, including serum folate (levels of folic acid in the blood), vitamin B12, and homocysteine (a harmful substance linked to heart and brain problems; lower is better), as well as reductions in inflammatory markers like IL-6, TNF-α, and MCP-1 (proteins that increase during inflammation in the body). They also had significant improvements in cognitive function, including Full Scale IQ (overall thinking ability), verbal IQ (language and understanding), Information (general knowledge), and Digit Span (memory and attention). Further analysis showed the combined vitamins were significantly more effective than folic acid alone. Overall, taking both vitamins for 6 months helped improve brain function and reduce inflammation in older adults with mild cognitive impairment.
To assess whether maternal vitamin B12 supplementation improves maternal B12 status and infant neurodevelopment in predominantly vegetarian populations
Study Type
Double-blind, multicentric randomized controlled trial
Purpose
To assess whether maternal vitamin B12 supplementation improves maternal B12 status and infant neurodevelopment in predominantly vegetarian populations
Dose
250 µg methyl-cobalamin daily vs 50 µg methyl-cobalamin daily
Participants
Pregnant women in first trimester from vegetarian populations (India and Nepal), followed through 6 months postpartum, with infant assessment at 9-12 months
Duration
From first trimester through 6 months postpartum, infant assessment at 9-12 months
Results
Higher dose B12 supplementation (250 µg) improved maternal and infant B12 status and significantly improved infant mental developmental quotient compared to lower dose (50 µg)
How They Measured It
Development Assessment Scale of Indian Infants, maternal and infant serum B12 levels
Cognitive Function
To evaluate homocysteine-lowering by B vitamins and effects on brain atrophy in mild cognitive impairment
Study Type
Randomised, controlled trial (VITACOG)
Purpose
To evaluate homocysteine-lowering by B vitamins and effects on brain atrophy in mild cognitive impairment
Dose
High-dose folic acid, vitamins B6 and B12
Participants
271 individuals over 70 years old with mild cognitive impairment
Duration
2 years
Results
Mean rate of brain atrophy 0.76% in active treatment vs 1.08% in placebo. Treatment response related to baseline homocysteine levels: 53% reduction in atrophy for those with elevated homocysteine.
How They Measured It
Brain atrophy rate on MRI, cognitive function
To evaluate efficacy of vitamin B supplementation on cognition in elderly patients with cognitive-related diseases
Study Type
Systematic review and meta-analysis
Purpose
To evaluate efficacy of vitamin B supplementation on cognition in elderly patients with cognitive-related diseases
Dose
Vitamin B12 (various doses)
Participants
Meta-analysis of multiple elderly cohorts
Duration
Various study durations
Results
B vitamins effectively lower homocysteine but show limited cognitive benefits, with more promising results in individuals with elevated baseline homocysteine levels.
How They Measured It
Cognitive function assessments from multiple RCTs
Neurological Health
To assess effect of B vitamins on global cognitive function in older adults
Study Type
Meta-analysis of randomized controlled trials
Purpose
To assess effect of B vitamins on global cognitive function in older adults
Dose
B vitamins including B12
Participants
Meta-analysis of studies in older adults
Duration
Various
Results
High-certainty evidence that vitamin B6, B9, or B12 supplementation has small benefit on global cognitive function in older adults.
How They Measured It
Global cognitive function scores
Frequently Asked Questions
Common questions about Vitamin B12 research
There are currently 6 peer-reviewed studies on Vitamin B12 (Vitamin B12), involving 637 total participants. Research covers Cognitive Health. The overall evidence strength is rated as Strong.
The evidence is currently rated as "Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (4 human studies), and reported outcomes.
Vitamin B12 has been researched for: Cognitive Health. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 4 out of 6 studies are human trials. Human trials carry more weight in our evidence scoring system.
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