OBJECTIVE: Patients with unexplained abdominal complaints often attribute their symptoms to intestinal gas and indicate that symptoms are exacerbated by ingestion of a meal. However, the mechanisms responsible are unknown. Our aim was to analyze the specific influence of two meal-related factors, gastric distension, and intestinal nutrients, on intestinal gas dynamics and tolerance. METHODS: In 35 healthy subjects, gas evacuation and perception of jejunal gas infusion (12 ml/min) were measured for 3 h, during simultaneous duodenal infusion of saline, as control, lipids at 1 Kcal/min, or gastric distension. RESULTS: Infusion of lipids into the duodenum induced gas retention (584 ± 154 ml, p < 0.05 vs 161 ± 86 ml after saline infusion) without perception (2.2 ± 0.5 score), whereas gastric distension induced perception (score 5.6 ± 0.4, p < 0.05 vs score 1.9 ± 0.4 after saline) without gas retention (7 ± 205 ml). CONCLUSIONS: Different meal-related factors exert specific effects on intestinal gas dynamics and tolerance, and these mechanisms may interact to produce postprandial gas symptoms. © 2002 by Am. Coll. of Gastroenterology.