Helicobacter pylori infection prevents nocturnal gastric acid breakthrough.

Background/aims: Nocturnal gastric acid breakthrough (NAB) is given attention as one of the factors that cause refractory reflux esophagitis. However, its clinical states and mechanisms are not yet clearly understood. We studied whether there will be a NAB outbreak or not among healthy Japanese male volunteers upon administration of omeprazole, as well as what kind of factors will be involved in case of an outbreak.

Methodology: Twenty-one volunteers were selected as subjects for this research. Subjects were checked for symptoms as well as for esophageal hiatal hernia, atrophic patterns and Helicobacter pylori infection of the gastric mucosa. We also conducted esophageal and gastric 24h pH monitoring twice before and after administration of 20mg omeprazole. We further studied CYP2C19 gene polymorphism.

Results: We observed NAB outbreak in 9 cases (42.9%) among 21 subjects. All 6 cases (100%) in the H. pylori-positive group showed NAB negative while 6 (40%) of the 15 cases in the H. pylori-negative group showed NAB negative. We found a statistically significant difference between these two groups (P=0.012). We also found a tendency that NAB outbreak is affected by CYP2C19 gene polymorphism.

Conclusions: H. pylori infection prevents NAB among healthy Japanese male volunteers under administration of omeprazole.