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• 1 Nicola Prochazkova et al. Advancing human gut microbiota research by considering gut transit time

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• By what is the composition and metabolism of the adult gut microbial communities affected?

  By a combination of factors
  

  • diet
  • demographics
  • use of medication
  • health status 
  • environmental components shaping the gut environment 
  • gut transit time 

• What is approximately the transit time in a healthy population?

  It varies substantially between individuals with a median whole gut transit time of approximately 28 hours

• With what is the gut transit time associated?

  Associated with gut microbial diversity, composition, and metabolism 
  
  the gut transit time, varies markedly between and within individuals 

• What are the segment-specific transit times?

  • Gastric emptying time (GET)
    
  • small intestinal transit time (SITT)
  • colonic transit time (CTT)

• Several factors affect the intraindividual and inter individual variations in gut transit time, which are?

  • Sex
    
  • ageing
  • stress
  • BMI
  • colonic anatomy
  • gut hormones 
  • diet 
  • as well as gut microbiota and its metabolites

• What can be said about cellulose and transit time?

  Cellulose, which is also non-fermentable (besides dietary fibres) but bot gel-forming, has been shown to lower faecal pH, increase the stool outputs and to disease CTT (=colonic transit time)

• How can water influence the transit time?

  The effects on transit time depend on the particle size, solubility, fermentability and viscosity of the given fibre. 
  Furthermore, water supplementation has been found to enhance the effect of high-fibre diet on increasing stool frequency in constipated patient, suggesting that fluid intake is another important factor to consider with respect to transit time. 

• What is the pH in the different ranges in the gut DuodenumIleum Ascending Descending 

  • Duodenum = 4.8-7.0 pH
  • Ileum  = 6.4-8.2 pH
  • Ascending  = 5.3-6.8 pH

  • Descending  = 6.6-8.0 pH

• What can you say about the length of the intestine?

  The length of the intestine is also an important factor to consider as it can vary greatly among individuals. Based on a postmortem measurement, men have been found to have a longer intestine than women, which may contribute to longer transit time in women.

• Stool consistency can be assessed by ?

  By the Bristol Stool Scale, which is a surrogate marker for CTT, has been identified as a top coverage of the faecal microbial composition of a health population.