US EPA

1664151 

Journal Article 

Chemical generation of nitric oxide in the mouth from the enterosalivary circulation of dietary nitrate 

Duncan, C; Dougall, H; Johnston, P; Green, S; Brogan, R; Leifert, C; Smith, L; Golden, M; Benjamin, N 

1995 

1 

Nature Medicine
ISSN: 1078-8956
EISSN: 1546-170X 

1 

6 

546-551 

English 

7585121 

10.1038/nm0695-546 

WOS:A1995RN10100038 

High concentrations of nitrite present in saliva (derived from dietary nitrate) may, upon acidification, generate nitrogen oxides in the stomach in sufficient amounts to provide protection from swallowed pathogens. We now show that, in the rat, reduction of nitrate to nitrite is confined to a specialized area on the posterior surface of the tongue, which is heavily colonized by bacteria, and that nitrate reduction is absent in germ-free rats. We also show that in humans increased salivary nitrite production resulting from nitrate intake enhances oral nitric oxide production. We propose that the salivary generation of nitrite is accomplished by a symbiotic relationship involving nitrate-reducing bacteria on the tongue surface, which is designed to provide host defence against microbial pathogens in the mouth and lower gut. These results provide further evidence for beneficial effects of dietary nitrate.