Presence of dietary fat in the distal ileum contributes to

• A. increased gastric emptying
• B. slowed intestinal transit
• C. bacterial fermentation
• D. production of short chain fatty acids

Answer: (B)

Fat in the distal ileum triggers the ileal brake, a feedback mechanism that slows intestinal transit to give fats more time to be absorbed. This slowdown is driven by hormones such as peptide YY and GLP-1 released in response to lipids in the ileum, which reduce motility and can also temper gastric emptying. So the presence of fat here mainly slows movement through the gut, rather than speeding it up. Bacterial fermentation and short-chain fatty acid production occur mainly in the colon from undigested carbohydrates, not directly from fat in the distal ileum.