Dietary Fiber & the gut Flashcards
ileoceacal chyme
The fluid like digested food that moves from small intestine to large intestine
Ceacum
Consider as beginning of teh large intestine.
The primary site for fermentation: converting soluble sugars into biomass
Where is the water and electrolytes reabsorbed
The byproduct of reabsorption ?
Through the colon
Relatively solid stool
Which parts of gut act as the reservior prior to stool evacuation ?
Descending and sigmoid colon
JH Kellogg suggested use of dietary fiber ?
Bran intake to increase stool bulk
Improve laxation (bowel movement)
Prevent disease
Colonic motility study
Africa unrefined diet had to longest intestinal transit time
> UK vegetrian (mixed diet) >African mixed diet > UK refined diet
Uk refined diet have the heaviest daily weight stools
> UK veg (mixed diet)> African mixed diet> Afr unrefined diet
Diverticular disease
In diverticular disease, small bulges or pockets (diverticula) develop in the lining of the intestine. Diverticulitis is when these pockets become inflamed or infected.
Out pouching of the bowel wall
Typically observed in sigmoid and descending colon in western populations
In eastern populations more prevalent in the ascending colon
Effect of dietary fibre on stool weight
insoluable fiber increase stool weight > soluble fiber > resistant starch
Dietary fibre and the gut flora
Dietary substrate ( NSP & resistant starch ) undergo bacterial fermentation (Microbed degrade the substrate)
bacterial mass & other end products (H2S- hydrogen sulfide, CH4- methane, H2 , CO2, Short chain fatty acid ) produced
SCFA produced in NSP bacterial fermentation
Butyrate: substrate for growth and metabolism of colonic mucosal cells
Acetate & propionate: absorbed & metabolised by liver, 75% of energy NSP
Function of colonic bateria fermentation
regulate chemical and physical properties of intraluminal environment
Development of colonic microbial function in early life
- Mucin breakdown
- Regulation of faecal tryptic activity
[tryptic: a proteolytic enzyme of the pancreatic juice] - Conversion of bilirubin to urobilinogen
[bilirubin: by product of aged RBC clearance]
[urobilinogen : byproduct of the reduction] - Cholesterol catabolism
- Organic acid production (Acetate buffer)
Colorectal cancer
Japanese and Indian population have low risk as their high NSP diet
High risk for diet with high energy intake/ high fat & fatty meat
small and large intestine have rapid cell turnover rates
3–6 days
