The relationship between gastric pH and the emptying of solid, semisolid and liquid meals

The effect of three different meal constituents, solid, semisolid and liquid, on gastric pH, recorded in the proximal and distal stomach, was evaluated in a prospective study of 20 normal volunteers. The solid and liquid were ingested together as one meal and the semisolid as another. Simultaneous recordings of the rate of gastric emptying of the isotopically labelled meal constituents and the gastric pH were made. The rate of gastric emptying was more rapid for the liquid and semisolid constituents (t_1/2= 35.6, range 9.8–103.3 min and 47.4, range 33.5–120 min, respectively) than for the solid meal constituent (t_1/2= 72.0, range 45.0–103.8 min), P < 0.01. Both the combined meal of solid and liquid and the semisolid meal produced a higher pH response in the proximal stomach than in the distal stomach (5.2, range 2.4–6.1 vs 2.9, range 0.8–5.3 and 5.9, range 4.3–6.6 vs 4.3, range 1.1–5.9), P < 0.01. There were significant correlations between the rate of gastric emptying of all three meal constituents and the decline phase in the gastric pH recorded at both the proximal and distal probes, P < 0.01 (Pearson's correlation). The strongest correlations were found between the rate of gastric emptying and the gastric pH recorded in the proximal stomach. The decline phase of gastric pH followed the emptying of semisolid more closely than the emptying of either solid or liquid.