The protective role of gastric acid.

This paper reviews the relationship between gastric acid secretion and infection and the protective role of gastric acid as a primary bactericidal barrier and modulator of gastrin section. Gastric acid is bactericidal at pH 3 or less, but reduction of acidity predisposes to infection with a wide variety of bacteria. Bacterial infections or hyperpyrexia may be associated with a marked reduction in gastric acid secretion, and Campylobacter pylori has been suggested as one cause of epidemic hypochlorhydria. Achlorhydria is also associated with hypergastrinaemia with levels 20-fold higher in pernicious anaemia patients than normal subjects. Treatment with antisecretory drugs is associated with hypergastrinaemia with gastrin levels 2- to 5-fold higher than with placebo, and the gastrin levels correlate with the degree of acid suppression. The possible relationship among infection, acid suppression, hypergastrinaemia, and the development of enterochromaffin cell hyperplasia and possible carcinogenesis is reviewed.