Effects of Changing Intestinal Transit Time on Gut Microbial Composition and Metabolism

Inclusion Criteria: * 18.5-30.0 kg/m2 BMI * Self-reported ≤3.5 spontaneous bowel movements per week * Willing to collect urine and stool samples at home and able to temporarily store them in their own freezer in a provided container. * Willing to eat the foods provided. * Owns a smartphone (iOS 11.0 and later or Android 5.0 and up) with access to the internet. Exclusion Criteria: * Pregnant or lactating women. * Diagnosis of irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), inflammatory bowel diseases (IBD), Gastrointestinal obstruction, or Ischemic colitis * Diagnosed constipation according to the ROME IV criteria * Intake of antibiotics ˂ 1month, or any medication that can affect the outcomes of the study * Regular use of diarrhea inhibitors or laxatives * Dysphagia * Any chronic disease that can affect the outcomes of the study or pose a risk when consuming Movicol * Intake of medications potentially altering gastric pH (proton pump inhibitors, histamine receptor antagonists, antacids) * Intake of medications potentially altering the gastrointestinal motility (prokinetics, antiemetic agents, anti-cholinergic agents, narcotic analgetics, nonsteroidal anti-inflammatory drugs, and peroral glucocorticoids) * Concurrent participation in another trial * Any condition that makes the project responsible researcher to doubt the feasibility of the volunteer´s participation