Abstract
The consortium of trillions of microorganisms that live inside the human gut are integral to health. Little has been done to collate and characterize the microbiome of children. A systematic review was undertaken to address this gap (PROSPERO ID: CRD42018109599). MEDLINE and EMBASE were searched using the keywords: “healthy preadolescent children” and “gut microbiome” to 31 August 2018. Of the 815 journal articles, 42 met the inclusion criteria. The primary outcome was the relative abundance of bacteria at the phylum, family, and genus taxonomic ranks. α-diversity, short chain fatty acid concentrations, diet, 16S rRNA sequencing region, and geographical location were documented. The preadolescent gut microbiome is dominated at the phylum level by Firmicutes (weighted overall average relative abundance = 51.1%) and Bacteroidetes (36.0%); genus level by Bacteroides (16.0%), Prevotella (8.69%), Faecalibacterium (7.51%), and Bifidobacterium (5.47%). Geographic location and 16S rRNA sequencing region were independently associated with microbial proportions. There was limited consensus between studies that reported α-diversity and short chain fatty acids. Broadly speaking, participants from non-Western locations, who were less likely to follow a Westernized dietary pattern, had higher α-diversity and SCFA concentrations. Confirmatory studies will increase the understanding of the composition and functional capacity of the preadolescent gut microbiome.
Highlights
The gut microbiota is a complex and dynamic environment containing 10–100 trillion microorganisms represented by 1000 species [1,2,3] involved in numerous biological processes
This review aims to capture a snapshot of the healthy pediatric gut microbiome using relative abundance data, and to better understand any associations with geographical location and region selected for sequencing and diet
The pediatric gut microbiome was characterized by high proportions of Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria at the phylum rank
Summary
The gut microbiota is a complex and dynamic environment containing 10–100 trillion microorganisms represented by 1000 species [1,2,3] involved in numerous biological processes They assist in the breakdown of foods into metabolically and functionally important metabolites, such as short chain fatty acids (SCFAs) [4] and vitamin K [5]. A lack of Bifidobacteria during infancy may result in the proliferation of pathogenic bacteria or a decrease in the nutritional status of the infant [7] Later in life, these microorganisms may play a role in the development or mediation of several acute and chronic illnesses [8]. This systematic review aims to summarize the Nutrients 2020, 12, 16; doi:10.3390/nu12010016 www.mdpi.com/journal/nutrients
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