Lecture 5 - Part 3

Question 1

Why is fibre used in disease prevention management?

Answer 1

Fermentable fibres act as a substrate for the bacterial community in the colon

 Through bacterial fermentation, short chain fatty acids (acetate, propionate, butyrate) are produced

 95% of SCFA generated in the colon are metabolized by the host body

Question 2

What are thee proposed mechanisms for fibre in the body?

Answer 2

absorb bile acids, promote excretion
 Decreases intraluminal pH which inhibits some pathogenic bacteria (i.e. Clostridium Difficile and Escherichia Coli)
 Increase fecal bulk
 Shortened fecal transit time
 Fermentation may release fibre-bound calcium
 Butyric acid appears to hinder cancer cells
 Insoluble fibres bind carcinogens
 Inhibition of cholesterol synthesis
 Favor H2O + electrolyte reabsorption

Question 3

What are the fibre requirements?

Answer 3

Female: 25g/d
Males: 38 g/d

Question 4

Why would you have a fibre restricted diet?

Answer 4

Decrease frequency & volume of feces

Increase intestinal transit time

Prevent blockage of stenosed GI tract

Question 5

What would you consume in a low fibre diet?

Answer 5

< 10 g fibre / day
 decrease indigestible CHO
 Well-cooked/canned fruits &amp; veg. 
 Refined breads &amp; cereals
 Omit legumes, seeds, nuts
 Avoid caffeine, prune juice, alcohol 
 As tolerated: spices, fat, lactose