It has been hypothesized that dietary nitrite augments the antimicrobial activity of gastric acid after conversion to nitric oxide and other reactive nitrogen intermediates, thus resulting in increased resistance against gastrointestinal infection. In this study, we showed that the reducing agents ascorbic acid and glutathione reduced the activity of acidified nitrite against Yersinia enterocolitica (P < 0.001). In contrast, iodide and thiocyanate increased the antimicrobial activity (P < 0.001), whereas hydroxyacids (citrate, lactate, and tartarate) had no measurable effects.