Altered salivary microbiota associated with high-sugar beverage consumption

Abstract

The human oral microbiome may alter oral and systemic disease risk. Consuming high sugar content beverages (HSB) can lead to caries development by altering the microbial composition in dental plaque, but little is known regarding HSB-specific oral microbial alterations. Therefore, we conducted a large, population-based study to examine associations of HSB intake with oral microbiome diversity and composition. Using mouthwash samples of 989 individuals in two nationwide U.S. cohorts, bacterial 16S rRNA genes were amplified, sequenced, and assigned to bacterial taxa. HSB intake was quantified from food frequency questionnaires as low (< 1 serving/week), medium (1-3 servings/week), or high (> 3 servings/week). We assessed overall bacterial diversity and presence of specific taxa with respect to HSB intake in each cohort separately and combined in a meta-analysis. Consistently in the two cohorts, we found lower species richness in high HSB consumers (> 3 cans/week) (p = 0.027), and that overall bacterial community profiles differed from those of non-consumers (PERMANOVA p = 0.040). Specifically, presence of a network of commensal bacteria (Lachnospiraceae, Peptostreptococcaceae, and Alloprevotella rava) was less common in high compared to non-consumers, as were other species including Campylobacter showae, Prevotella oulorum, and Mycoplasma faucium. Presence of acidogenic bacteria Bifodobacteriaceae and Lactobacillus rhamnosus was more common in high consumers. Abundance of Fusobacteriales and its genus Leptotrichia, Lachnoanaerobaculum sp., and Campylobacter were lower with higher HSB consumption, and their abundances were correlated. No significant interaction was found for these associations with diabetic status or with microbial markers for caries (S. mutans) and periodontitis (P. gingivalis). Our results suggest that soft drink intake may alter the salivary microbiota, with consistent results across two independent cohorts. The observed perturbations of overrepresented acidogenic bacteria and underrepresented commensal bacteria in high HSB consumers may have implications for oral and systemic disease risk.

Keywords: High-sugar beverage consumption; Oral health; Oral microbiome; Population-based study; Salivary microbiota; Soda.

Figure 1

Richness and evenness of the oral microbiome by high-sugar beverage intake. (a,b) Violin plots of (a) number of observed OTUs (richness) and (b) inverse Simpson’s Index (evenness) by high-sugar beverage intake. These indices were calculated for 500 iterations of rarefied OTU tables of 2,027 sequence reads per sample, and the average over the iterations was taken for each participant. Plotted are median, interquartile ranges, and the probability density of the indices at different values. Mean values of the richness in non-drinker, low (< 1 can/week), moderate (1–3 cans/week), and high (> 3 cans/week) intake groups were 102.7, 106.0, 102.7, and 97.2; p = 0.51, 0.41, and 0.027 for each intake level compared to non-drinkers, and p = 0.032 for the trend test in linear regression model. Mean values of the inverse Simpson's Index in each group were 10.1, 10.5, 10.5, and 10.6; inverse Simpson’s index did not differ significantly by high-sugar beverage intake. (c,d) Rarefaction curves of (c) number of observed OTUs and (d) inverse Simpson’s Index according to the number of reads per sample, by high-sugar beverage intake group.

Figure 2

Principal Coordinate Analysis (PCoA) showing β-diversity of oral bacterial communities by high-sugar beverage intake. (a-b) PCoA plots using (a) unweighted and (b) weighted UniFrac phylogenetic distance matrices in all study participants. The community structures in non-drinkers and low- (< 1 can/week), moderate- (1–3 cans/week), and high- (> 3 cans/week) high-sugar beverage intake groups are depicted using different colors. Larger filled shapes indicate centroids for each group. (c,d) Barplots of the mean of the first three coordinates of PCoA by high-sugar beverage intake, using (c) unweighted and (d) weighted UniFrac phylogenetic distance matrices. In Adonis analysis, p-values for each high-sugar beverage intake group compared to non-drinkers were 0.10, 0.83, 0.44, and 0.040 using unweighted UniFrac (Kruskal–Wallis p-values = 0.003, 0.003, and 0.019, respectively), and 0.86, 0.18, 0.91, and 0.94 using weighted UniFrac (Kruskal–Wallis p-values n.s.). One star (*) indicates p < 0.05 in the Kruskal–Wallis post-hoc test (Dunn's test).

Figure 3

Co-occurrence and correlation networks in the oral bacterial community. (a,b) Co-occurrence and correlation network plots using (a) carriage rate and (b) abundance of taxa shown in Tables 2–3, as well as bacterial makers for caries and periodontitis. The nodes represent taxa, and edges with Spearman’s correlation coefficient |r|> 0.3 using all subjects are shown. Blue nodes represent taxa differentially carried by high-sugar beverage intake (Table 2); yellow nodes represent taxa differentially abundant by high-sugar beverage intake (Table 3); and purple nodes represent S. mutans and P. gingivalis, bacterial makers of caries and periodontitis. The thickness of edges corresponds to the coefficient values.