Impact of a vegan diet on the human salivary microbiota

Tue H Hansen,Emilie G Bak,Oluf Pedersen,Torben Hansen,Timo Kern,Trine Nielsen,Kristine H Allin,Alireza Kashani

doi:10.1038/s41598-018-24207-3

Abstract

Little is known about the effect of long-term diet patterns on the composition and functional potential of the human salivary microbiota. In the present study, we sought to contribute to the ongoing elucidation of dietary effects on the oral microbial community by examining the diversity, composition and functional potential of the salivary microbiota in 160 healthy vegans and omnivores using 16S rRNA gene amplicon sequencing. We further sought to identify bacterial taxa in saliva associated with host inflammatory markers. We show that compositional differences in the salivary microbiota of vegans and omnivores is present at all taxonomic levels below phylum level and includes upper respiratory tract commensals (e.g. Neisseria subflava, Haemophilus parainfluenzae, and Rothia mucilaginosa) and species associated with periodontal disease (e.g. Campylobacter rectus and Porphyromonas endodontalis). Dietary intake of medium chain fatty acids, piscine mono- and polyunsaturated fatty acids, and dietary fibre was associated with bacterial diversity, community structure, as well as relative abundance of several species-level operational taxonomic units. Analysis of imputed genomic potential revealed several metabolic pathways differentially abundant in vegans and omnivores indicating possible effects of macro- and micro-nutrient intake. We also show that certain oral bacteria are associated with the systemic inflammatory state of the host.

Highlights

Dietary effects on the human gut microbiota have been extensively studied, and long-term dietary habits have been shown to affect the diversity and composition of the human gut microbiota[1,2]
We identified 12 operational taxonomic units (OTU) that were present in all individuals (Supplementary Table S2)
Among these were OTUs assigned to Neisseria subflava, Haemophilus parainfluenzae, Prevotella melaninogenica, Veillonella dispar and Veillonella parvula, as well as unclassified Streptococcus spp., Granulicatella spp. and Campylobacter spp

Summary

Introduction

Dietary effects on the human gut microbiota have been extensively studied, and long-term dietary habits have been shown to affect the diversity and composition of the human gut microbiota[1,2]. The only study directly investigating the long-term effect of diet on the salivary microbiota compared 51 Italian vegans, 55 lacto-ovo vegetarians and 55 omnivores[5]. In spite of major differences in the macro- and micronutrient content of these diets, no difference in diversity, community structure, or taxonomic composition was observed and the authors concluded that long-term dietary habits have no effect in shaping the salivary microbiota. In a study of oral microbiota obtained by mouth swab from 62 patients with atherosclerosis and 30 healthy controls, Fåk and colleagues reported a weak positive correlation between genus Parvimonas and high sensitive C-reactive protein (CRP), thereby directly linking the oral microbiota to low-grade inflammation in cardiovascular disease. We sought to contribute to the ongoing elucidation of dietary effects on the oral microbial community by examining the diversity, composition and functional potential of the salivary microbiota in 78 healthy vegans and 82 healthy omnivores. We further sought to identify oral bacterial taxa associated with markers of systemic low-grade inflammation

Methods

Results

Conclusion