In this study the investigators aim to investigate the changes of the intestinal microbiome in three different cohorts (IBD, IBS, healthy) after applying the uniform disruptive factor of osmotic diarrhea induced by macrogol. The investigators hypothesis is that ill people will show more severe changes of the microbiome than healthy people and that these changes persist longer.

I

Inclusion Criteria:

• patients with inflammatory bowel disease and irritable bowel syndrome and stable therapy since three months
• patients with the indication for colonoscopy

Exclusion Criteria:

• age under 18
• pregnancy
• new therapy planned
• change of therapy within the last three months
• acute exacerbation of the inflammatory bowel disease
• colon pathologies of other origin: colocarcinoma, Illnesses with diarrhea (f.e.microscopic colitis), short bowel syndrome, malabsorption, colectomy
• intake of antibiotics in the last three months
• intake of probiotics in the last month
• intake of antibiotics or probiotics during the study
• new proton pump inhibitor therapy
• significant change of nutrition in the last three months
• holidays outside europe in the last month
• gastroenteritis in the last three months
• intake of laxatives
• nonsteroidal antiinflammatory drugs should be avoided and documented