Regional postprandial differences in pH within the stomach and gastroesophageal junction.

Our objective was to determine regional differences in intragastric pH after different types of meals. Ten normal subjects underwent 27-hr esophagogastric pH monitoring using a four-probe pH catheter. Meals were a spicy lunch, a high-fat dinner, and a typical bland breakfast. The fatty dinner had the highest postprandial buffering effect, elevating proximal and mid/distal gastric pH to 4.9 +/- 0.4 and 4.0 +/- 0.4, respectively, significantly (P < 0.05) higher compared to 4.2 +/- 0.3 and 3.0 +/- 0.4 for the spicy lunch and 3.0 +/- 0.3 and 2.5 +/- 0.8 for the breakfast. The buffering effect of the high-volume fatty meal to pH > 4 was also longer (150 min) compared to that of the spicy lunch (45 min) and the bland breakfast, which did not increase gastric pH to > 4 at any time. Proximal gastric acid pockets were seen between 15 and 90 min postprandially. These were located 3.4 +/- 0.8 cm below the proximal LES border, extending for a length of 2.3 +/- 0.8 cm, with a drop in mean pH from 4.7 +/- 0.4 to 1.5 +/- 0.9. Acid pockets were seen equally after the spicy lunch and fatty dinner but less frequently after the bland breakfast. We conclude that a high-volume fatty meal has the highest buffering effect on gastric pH compared to a spicy lunch or a bland breakfast. Buffering effects of meals are significantly higher in the proximal than in the mid/distal stomach. Despite the intragastric buffering effect of meals, focal areas of acidity were observed in the region of the cardia-gastroesophageal junction during the postprandial period.