Chapter 4 - Fiber

1
Chapter 4 - Fiber

• Objectives
• Learn the differences between dietary fiber and
  functional fiber and be able to give an example
  of each
• Understand how fiber in our diet is obtained,
  where it is located in plants, and why it is
  beneficial to our health
• Learn how the chemical structure of fibers
  influences their function in nutrition
• Understand the metabolic and physiologic effects
  of fiber
• Solubility
• Water holding capacity
• Adsorption
• Appreciate how fiber can be used in the
  management and prevention of disease
• Diabetes
• Heart disease
• GI disorders
• Cancers

2
Dietary Fiber Functional Fiber Soluble
Fiber Insoluble fiber
05CO, p. 108
3
Table 5-1, p. 109
4
(No Transcript)
5
Fig. 5-1a, p. 110
6
Fig. 5-1b, p. 110
7
Fig. 5-1c, p. 110
8
Fig. 5-1d, p. 110
9
Fig. 5-1e, p. 110
10
Fig. 5-1f, p. 110
11
Fig. 5-2, p. 113
12
Fig. 5-3, p. 114
13

• High fiber 5 g or more per serving
• Good source of fiber 2.5 g to 4.9 g per serving
• More or added fiber At least 2.5 g more per
  serving than the reference food

14
(No Transcript)
15
(No Transcript)
16

• High bile acid concentrations are associated with
  a high risk of colon cancer. Thus, fibers that
  adsorb bile acids to promote fecal excretion
  serve a protective effect
• Fibers that increase fecal bulk decrease the
  intraluminal concentrations of carcinogens and
  thereby reduce the likelihood of interactions
  with colonic mucosal cells.
• Allowance of a fermentable substrate to colonic
  bacteria alters kinds and numbers of bacteria
  and/or their metabolism, which may inhibit
  proliferation or development of tumor cells or
  conversion of procarinogens to carcinogens.
• A shortened fecal transit time decreases the time
  during which toxins can be synthesized and in
  which they are in contact with the colon.
• Fiber fermentation to short-chain fatty acids
  decreases the interluminal pH, thereby decreasing
  synthesis of secondary bile acids, which have
  been shown to promote the generation of tumors.
• Degradation of fiber by fermentation may release
  fiber-bound calcium. The increased calcium in the
  colon may help eliminate the mitogenic advantage
  that cancer cells have over normal cells in a
  low-calcium environment.
• Butyric acid appears to slow the proliferation
  and differentiation of colon cancer cells.
• Insoluble fibers such as lignin that resist
  degradation bind carcinogens, thereby minimizing
  the chances of interactions with colonic mucosal
  cells.