Vitamin B-12 and the Gastrointestinal Microbiome: A Systematic Review

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Vitamin B-12 and the Gastrointestinal Microbiome: A Systematic Review

Guetterman et al., 2022 | Adv Nutr | Systematic Review

Citation

Guetterman Heather M, Huey Samantha L, ... Finkelstein Julia L. Vitamin B-12 and the Gastrointestinal Microbiome: A Systematic Review. Adv Nutr. 2022-Mar;13(2):530-558. doi:10.1093/advances/nmab123

Abstract

Vitamin B-12 deficiency is a major public health problem affecting individuals across the lifespan, with known hematological, neurological, and obstetric consequences. Emerging evidence suggests that vitamin B-12 may have an important role in other aspects of human health, including the composition and function of the gastrointestinal (gut) microbiome. Vitamin B-12 is synthesized and utilized by bacteria in the human gut microbiome and is required for over a dozen enzymes in bacteria, compared to only 2 in humans. However, the impact of vitamin B-12 on the gut microbiome has not been established. This systematic review was conducted to examine the evidence that links vitamin B-12 and the gut microbiome. A structured search strategy was used to identify in vitro, animal, and human studies that assessed vitamin B-12 status, dietary intake, or supplementation, and the gut microbiome using culture-independent techniques. A total of 22 studies (3 in vitro, 8 animal, 11 human observational studies) were included. Nineteen studies reported that vitamin B-12 intake, status, or supplementation was associated with gut microbiome outcomes, including beta-diversity, alpha-diversity, relative abundance of bacteria, functional capacity, or short-chain fatty acids (SCFA) production. Evidence suggests that vitamin B-12 may be associated with changes in bacterial abundance. While results from in vitro studies suggest that vitamin B-12 may increase alpha-diversity and shift gut microbiome composition (beta-diversity), findings from animal studies and observational human studies were heterogeneous. Based on evidence from in vitro and animal studies, microbiome outcomes may differ by cobalamin form and co-intervention. To date, few prospective observational studies and no randomized trials have been conducted to examine the effects of vitamin B-12 on the human gut microbiome. The impact of vitamin B-12 on the gut microbiome needs to be elucidated to inform screening and public health interventions.

Key Findings

The impact of vitamin B-12 on the gut microbiome needs to be elucidated to inform screening and public health interventions.

Outcomes Measured

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Population

Field Value
Population See abstract
Sample Size 22
Age Range See abstract
Condition deficiency

MeSH Terms

  • Animals
  • Humans
  • Gastrointestinal Microbiome
  • Vitamin B 12
  • Microbiota
  • Eating
  • Bacteria
  • Vitamins
  • Observational Studies as Topic

Evidence Classification

  • Level: Systematic Review
  • Publication Types: Systematic Review, Journal Article, Research Support, N.I.H., Extramural
  • Vertical: vitamin-b12

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09