Vitamin B12 and Improved Cognitive Function

Research synthesisLow evidenceSmall effect3 studies · 1 beneficial · 2 neutral · 0 harmful

Across 3 studies, 2 reported neutral effects (small effect size) and 1 reported a beneficial effect (small effect size). The only statistically significant finding came from a systematic review that did not isolate vitamin B12 from other supplements. The evidence does not support a clear benefit of vitamin B12 for cognitive function in general populations, and effects are predominantly neutral with small magnitude.

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Only 1 of 3 studies reported statistically significant findings, and that study did not isolate B12's specific effect (systematic review covering multiple vitamins). The neutral meta-analysis in children was based on low-certainty evidence, and the neutral RCT in schizophrenia had a small sample size. No form data was reported, so form-specific effects cannot be assessed.

Generated Jul 12, 2026

Doses used in studies

µg/day: 0.9–150 (median 75.45, IQR 0.9–150) — 1 study
μg/day: 500 (median 500, IQR 500–500) — 1 study

Time to effect

Median: 5.6 months · IQR 5.6 months–5.6 months · Range 5.6 months–5.6 months — Reported in 1 of 3 studies

Safety in these studies

Overall tolerabilityReported
No trials reported the occurrence of any adverse effects.
from: Vitamin B12 supplementation for growth, development, and cognition in children.

3 of 3 papersPopulation:

Vitamin B12 supplementation for growth, development, and cognition in children.
- 2026-06-02
- Meta-Analysis · n = 4,083
- The Cochrane database of systematic reviews 2026(6)
- - Doreen Y Larvie
  - Cristina E Güitrón Leal
  - Sudha Venkatramanan
  - Ximena E Palma Molina
  - Lili B Steel
  - Rebecca Kuriyan
  - Julia L Finkelstein
- PubMed: 42227307
- DOI: 10.1002/14651858.cd015264.pub2
6 Insights on
- Improved Cognitive Function
- High evidence
- Children
There may be little to no difference between groups in cognitive function (e.g. attention) (standardised mean difference (SMD) 0.09, 95% CI -0.10 to 0.28; 2 trials, 438 children, low-certainty evidence)
Effect
Neutral
Effect size
Small
Significant
No
Dose
0.9 µg/day to 150 µg/day
Vitamin Supplementation and Dementia: A Systematic Review.
- 2022-02-28
- Systematic Review
- Nutrients 14(5)
- - Victoria Gil Martínez
  - Ana Avedillo Salas
  - Sonia Santander Ballestín
- PubMed: 35268010
- DOI: 10.3390/nu14051033
1 Insight on
- Improved Cognitive Function
- High evidence
- Rigorous Journal
Ascorbic acid and a high dose of vitamin E, when given separately, also showed positive effects on cognitive performance, but there is not sufficient evidence to support their use.
Effect
Beneficial
Effect size
Small
Significant
Yes
Folate and vitamin B12 supplementation in patients with schizophrenia and low serum folate level: A 24-week randomized, double-blind, placebo-controlled study.
- 2026-01
- RCT · n = 36
- Journal of the Formosan Medical Association = Taiwan yi zhi 125(1)
- - Chun-Hsin Chen
  - Chih-Chiang Chiu
  - Yi-Hang Chiu
  - Chin-Hao Chang
  - Yu-Han Chang
  - Ming-Chyi Huang
  - Mong-Liang Lu
  - Po-Yu Chen
- PubMed: 39645464
- DOI: 10.1016/j.jfma.2024.11.019
2 Insights on
- Improved Cognitive Function
- High evidence
- Clinical
There were no significant changes in scores of total and each subscale of PANSS, and Cogstate between the folate and placebo groups.
Effect
Neutral
Effect size
Small
Significant
No
Dose
500 μg/day

Vitamin B12 and Improved Cognitive Function

Vitamin B12 supplementation for growth, development, and cognition in children.

Vitamin Supplementation and Dementia: A Systematic Review.

Folate and vitamin B12 supplementation in patients with schizophrenia and low serum folate level: A 24-week randomized, double-blind, placebo-controlled study.