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

Vitamin B-12 and the Gastrointestinal Microbiome: A Systematic Review 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 two 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 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 acid production. Evidence suggests vitamin B-12 may be associated with changes in bacterial abundance. While results from in vitro studies suggest 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. Statement of significance: Vitamin B-12 is synthesized and utilized by bacteria in the human gut microbiome and is required by over a dozen enzymes in bacteria. However, to date, no systematic reviews have been conducted to evaluate the impact of vitamin B-12 on the gut microbiome, or its implications for human health. vitamin b-12, cobalamin, gut microbiota, microbiome, systematic review Notes H.M.G. was supported by the National Institutes of Health under award T32-DK007158. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Author disclosures: The authors have no conflicts of interest to disclose related to this review. S.M. is an unpaid board member for and has an equity stake in a diagnostic start-up focused on developing point-of-care assays for nutritional status informed by his research as a faculty member at Cornell University. Abbreviations used: ACE, abundance-based coverage estimators; CoA, coenzyme A; MeSH, Medical Subject Heading; OTU, operational taxonomic unit; PCA, principal components analysis; PCoA, principal coordinates analysis; SAM, S-adenosylmethionine; SCFA, short chain fatty acid; T-RFLP, terminal restriction fragment length polymorphism © The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Advances in Nutrition Oxford University Press

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

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Publisher
Oxford University Press
Copyright
Copyright © 2021 American Society for Nutrition
ISSN
2161-8313
eISSN
2156-5376
DOI
10.1093/advances/nmab123
Publisher site
See Article on Publisher Site

Abstract

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 two 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 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 acid production. Evidence suggests vitamin B-12 may be associated with changes in bacterial abundance. While results from in vitro studies suggest 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. Statement of significance: Vitamin B-12 is synthesized and utilized by bacteria in the human gut microbiome and is required by over a dozen enzymes in bacteria. However, to date, no systematic reviews have been conducted to evaluate the impact of vitamin B-12 on the gut microbiome, or its implications for human health. vitamin b-12, cobalamin, gut microbiota, microbiome, systematic review Notes H.M.G. was supported by the National Institutes of Health under award T32-DK007158. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Author disclosures: The authors have no conflicts of interest to disclose related to this review. S.M. is an unpaid board member for and has an equity stake in a diagnostic start-up focused on developing point-of-care assays for nutritional status informed by his research as a faculty member at Cornell University. Abbreviations used: ACE, abundance-based coverage estimators; CoA, coenzyme A; MeSH, Medical Subject Heading; OTU, operational taxonomic unit; PCA, principal components analysis; PCoA, principal coordinates analysis; SAM, S-adenosylmethionine; SCFA, short chain fatty acid; T-RFLP, terminal restriction fragment length polymorphism © The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

Advances in NutritionOxford University Press

Published: Oct 6, 2021

Keywords: vitamin b12; cobalamin; microbiome; intestinal bacteria; bacteria

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