Nitrate-rich diet alters the composition of the oral microbiota in periodontal recall patients

Abstract

Background: This follow-up study evaluated microbiome changes in periodontal recall patients after consuming a nitrate-rich diet that led to a marked decrease of gingival inflammation. Methods: Subgingival microbial samples of 37 patients suffering from gingival inflammation with reduced periodontium were taken before professional mechanical plaque removal (baseline) and subsequently after 2 weeks of regularly consuming a lettuce juice beverage (day 14) containing a daily dosage of 200 mg of nitrate (test group, n = 18) or being void of nitrate (placebo group, n = 19). Three hundred base pairs paired-end sequencing of the V3‒V4 hypervariable region of the 16S rDNA was performed. Results: At baseline, there were no significant differences about the bacterial diversity parameters between the groups (Mann-Whitney U test). After intervention in the test group, Rothia and Neisseria, including species reducing nitrate, increased significantly (negative binomial regression model). Alpha diversity decreased significantly from 115.69 ± 24.30 to 96.42 ± 24.82 aRSVs/sample (P = 0.04, Wilcoxon signed-rank test), accompanied by a significant change in beta diversity (P < 0.001, PERMANOVA). In the control group, however, no genus changed significantly, and alpha-, as well as beta-diversity did not change significantly. Conclusions: The decrease of gingival inflammation in periodontal recall patients induced by a nitrate-rich diet is accompanied by significant compositional changes within the subgingival microbiome.