Racial differences in gastric function among African Americans and Caucasian Americans: secretion, serum gastrin, and histology.

We measured gastric juice fluid output, acidity, tonic strength (osmolality), and pepsin concentrations basally and after the injection of pentagastrin in 120 healthy African Americans and 60 Caucasian Americans of similar age and gender. Sera for basal gastrin concentration and IgG for antibody to Helicobacter pylori (Hp) organisms also were obtained, as were gastric body mucosal biopsies to ascertain the presence or absence of Hp or gastritis. Gastric juice hydrogen ion concentrations and osmolality were significantly lower in African Americans than in Caucasians. At the same time, African Americans had significantly higher gastric juice fluid outputs than did Caucasians. From measurements of gastric juice fluid output, acidity, and osmolality, we used a previously validated method for calculating gastric HCO3- and H+ secretion, as well as nonparietal and parietal fluid secretion. Gastric HCO3 secretion and nonparietal fluid were significantly higher in African Americans, while H+, parietal fluid, and pepsin secretion rates were nearly identical in the two racial groups. Basal serum gastrin concentrations and antibody titers to Hp also were significantly higher in African Americans (p < .001). Mucosal biopsies demonstrated a much higher prevalence of Hp infection and chronic active superficial gastritis in African Americans than Caucasians (p < .001). When only Hp-negative subjects were considered, racial differences in gastric secretion and basal serum gastrin concentration were still present. The mechanism or mechanisms causing higher gastric bicarbonate and nonparietal fluid secretion and for higher serum gastrin concentrations in African Americans remains to be elucidated.