Ileal brake activation: macronutrient-specific effects on eating behavior?

Background: Activation of the ileal brake, by infusing lipid directly into the distal part of the small intestine, alters gastrointestinal (GI) motility and inhibits food intake. The ileal brake effect on eating behavior of the other macronutrients is currently unknown. Objective: The objective of this study was to investigate the effects of ileal infusion of sucrose and casein on food intake, release of GI peptides, gastric emptying rate and small-bowel transit time with safflower oil as positive control. Design: This randomized, single-blind, crossover study was performed in 13 healthy subjects (6 male; mean age 26.4±2.9 years; mean body mass index 22.8±0.4 kg m −2 ) who were intubated with a naso–ileal catheter. Thirty minutes after the intake of a standardized breakfast, participants received an ileal infusion, containing control ((C) saline), safflower oil ((HL) 51.7 kcal), low-dose casein ((LP) 17.2 kcal) or high-dose casein ((HP) 51.7 kcal), low-dose sucrose ((LC) 17.2 kcal) and high-dose sucrose ((HC) 51.7 kcal), over a period of 90 min. Food intake was determined during an ad libitum meal. Visual analogue score questionnaires for hunger and satiety and blood samples were collected at regular intervals. Results: Ileal infusion of lipid, protein and carbohydrate resulted in a significant reduction in food intake compared with control (HL: 464.3±90.7 kcal, P