Nutrition Support and the Gastrointestinal Microbiota: A Systematic Review.

Background Low microbial diversity or altered microbiota composition is associated with many disease states. In the treatment of many conditions, enteral (EN) or parenteral (PN) nutrition is frequently required. Objective This systematic review aimed to identify and evaluate the evidence of the effect of EN vs PN on the gastrointestinal microbiota. Method A comprehensive systematic literature search of 5 databases was completed to review studies published until February 2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were utilized in completion of the review with the Academy of Nutrition and Dietetics quality criteria checklist and Grading of Recommendations Assessment, Development and Evaluation to evaluate the included studies. The review was registered on PROSPERO (CRD42018091328). Studies were eligible for inclusion if participants were older than 3 years, patients received either EN, PN or both, with some patients receiving each mode of nutrition support. The main outcome was any assessment of the gastrointestinal microbiota, including diversity or taxa abundance. Results Eleven articles (n = 367 patients) met the inclusion criteria and were evaluated. Seven studies (n = 237) reported greater abundance of Proteobacteria with the provision of PN compared to EN; 6 studies (n = 172) reported lower Firmicutes and 5 studies (n = 155) lower Bacteroidetes. In 7 studies (n = 282), microbial diversity was lower with provision of PN than EN. The Grading of Recommendations Assessment, Development and Evaluation certainty of evidence was very low. Conclusions Provision of PN may lead to greater abundance of Proteobacteria and reduced microbial diversity; however, there is limited literature on this topic and additional research is warranted to improve understanding of the impact of EN vs PN on the microbiota.