Absorption of Peptides, Fluid, and Electrolytes in Patients With an Ileostomy

Inclusion Criteria: * Adult (≥ 18 years old), male or female patients with an ileostomy and intestinal insufficiency * Episodical or chronic sodium depletion defined by two urine samples with sodium levels ≤ 20 mmol/L, sampled with at least 28 days apart * Six months or more after most recent bowel surgery * If inflammatory bowel disease, no clinical signs of activity (any treatment allowed except systemic steroids \> 10 mg/day) Exclusion Criteria: * Parenteral nutrition or intravenous fluid support ≥ 4000 mL/month * Ongoing infection (C-reactive protein above 8 mg/L or core temperature \>38.0°C) * Self-reported intolerance to dairy products, including lactose intolerance * Inability to understand Danish or the trial procedures * Known or anticipated pregnancy * Known severe renal insufficiency (eGFR \< 20 mL/min) * Known diabetes mellitus (HbA1c ≥ 48 mmol/mol (6.5%)) * Pacemaker, cochlear implants, or other electrical implants excludes the participants from BIA-measurements and measurements of GITT with 3D-Transit capsules, but not the remaining investigations * Known intestinal stenosis or parastomal hernia excludes measurements of GITT with 3D-Transit capsules, but not the remaining investigations * Abdominal diameter \> 140 cm, or planned MR scan four weeks following participation excludes measurements of GITT with 3D-Transit capsules, but not the remaining investigations