The role of mastication on digestion efficiency remains to be demonstrated. This study investigates whether masticatory function influences gastric emptying rate. Twelve normal volunteers were studied on two occasions after ingestion of the same test meal containing ham cubes, crackers, and egg (mixed with 13C-octanoic acid), chewed, in random order, either with 50 masticatory cycles or with 25 cycles, swallowing ham cubes whole. Lag phase (Tlag) and gastric half-emptying time (T1/2) were measured by means of the 13C-octanoic acid breath test. Trituration performance was assessed by the sieve test, and was expressed as the percentage of ham particles < or = 1 mm after 50 masticatory cycles. Tlag and T1/2 were significantly shorter when the meal was chewed with 50 cycles than with 25 cycles (Tlag 25.9+/-3.8 vs. 36.4+/-4.1 min, p=0.017; T1/2 49.1+/-5.7 vs. 62.5+/-6 min, p=0.009). Trituration performance was inversely related to both Tlag (r=0.621, p=0.031) and T1/2 (r=0.699, p=0.012). Comminution of food influences significantly gastric emptying rates.