Sustaining elevated levels of nitrite in the oral cavity through consumption of nitrate-rich beetroot juice in young healthy adults reduces salivary pH

Abstract

Background: Dietary inorganic nitrate (NO₃^-) and its reduced forms nitrite (NO₂^-) and nitric oxide (NO), respectively, are of critical importance for host defense in the oral cavity. High concentrations of salivary nitrate are linked to a lower prevalence of caries due to growth inhibition of cariogenic bacteria.

Objective: In-vitro studies suggest that the formation of antimicrobial NO results in an increase of the pH preventing erosion of tooth enamel. The purpose of this study was to prove this effect in-vivo.

Methods: In a randomized clinical study with 46 subjects we investigated whether NO₃^- rich beetroot juice exhibits a protective effect against caries by an increase of salivary pH.

Results: Our results show that, in comparison to a placebo group, consumption of beetroot juice that contains 4000 mg/L NO₃^- results in elevated levels of salivary NO₂^-, nitrite NO₃^-, and NO. Furthermore, we determined an increase of the mean pH of saliva from 7.0 to 7.5, confirming the anti-cariogenic effect of the used NO₃^--rich beetroot juice.

Conclusions: Taken together, we have found that NO₃^--rich beetroot juice holds potential effects against dental caries by preventing acidification of human saliva.

Trial registration: C-87-15 (Ethics Commissions of Upper Austria).

Keywords: Beetroot juice; Caries; Nitrate; Nitric oxide; Nitrite; Salivary pH.