The effects of nitrate on the oral microbiome: a systematic review investigating prebiotic potential.

Background: Nitrate (NO) has been suggested as a prebiotic for oral health. Evidence indicates dietary nitrate and nitrate supplements can increase the proportion of bacterial genera associated with positive oral health whilst reducing bacteria implicated in oral disease(s). In contrast, chlorhexidine-containing mouthwashes, which are commonly used to treat oral infections, promote dysbiosis of the natural microflora and may induce antimicrobial resistance.

Methods: A systematic review of the literature was undertaken, surrounding the effects of nitrate on the oral microbiota.

Results: Overall,  = 12 and studies found acute and chronic nitrate exposure increased (representatives of) health-associated and (67% and 58% of studies, respectively) whilst reducing periodontal disease-associated (33%). Additionally, caries-associated and decreased (25% for both genera). Nitrate also altered oral microbiome metabolism, causing an increase in pH levels ( = 5), which is beneficial to limit caries development. Secondary findings highlighted the benefits of nitrate for systemic health ( = 5).

Conclusions: More clinical trials are required to confirm the impact of nitrate on oral communities. However, these findings support the hypothesis that nitrate could be used as an oral health prebiotic. Future studies should investigate whether chlorhexidine-containing mouthwashes could be replaced or complemented by a nitrate-rich diet or nitrate supplementation.