~4 - 6 hours
||Human Homo sapiens
||G. T. Macfarlane and G. R. Gibson, Metabolic Activities of the Normal Colonic Flora, chapter 2 in Human Health: The Contribution of Microorganisms, Edited by S. A. W. Gibson, Springer-Verlag 1994 link , p.17 bottom paragraph
||Gorbach SL (1967) Population control in the small bowel. Gut 8: 530-532PubMed ID4866862
||P.17 bottom paragraph: "In persons living in Western countries, the main areas of permanent colonisation of the
gastrointestinal tract are the terminal ileum and large intestine. This is mainly because gastric acid kills many microorganisms in the stomach, thereby reducing numbers
entering the small bowel. However, rapid passage of digesta through the stomach and small bowel (approximately 4 h - 6 h) also prevents the establishment of significant microbial populations in these regions (primary source)."