Dietary fibers

Definition: fibers are non-digestible, non-starch polysaccharide derived from plant sources which undergo partial fermentation in colon and totally excreted with feces.

Type of dietary fibers:

1.      Depending on chemical nature:

a.      Nonstarch polysaccharide: Cellulose, Hemicellulose, pectins, gums.

b.      Resistant starch: Milled grains, raw potato, green banana.

c.       Fructo-oligosaccharide: Onion, Garlic

d.      Lignin and cutin: Woody vegetables.

2.      Depending on solubility

a.      Soluble dietary fibers: Pectins, Gums, Cutins

b.      Insoluble dietary fibers: Cellulose, Hemicellulose.

Properties of dietary fibers:

1.      Hydrophilic

2.      Forms highly viscous solution with water

3.      Susceptible to fermentation by colonic bacteria producing short chain fatty acids.

4.      Binds with bile acids and facilitates their fecal excretion

5.      Binds with minerals and prevents their absorption in gut

6.      Stimulates bacterial proliferation in gut.

Clinical importance of dietary fibers:

1.      Improves bowel function and maintains regular bowel habit by preventing constipation.

2.      Decreased the risk of atherosclerotic disorders by reducing plasma cholesterol concentration through increased fecal excretion of cholesterol as bile acid.

3.      Increase glucose tolerance and thereby reduces the risk of DM.

4.      Reduces the body weight and prevents the risk of obesity.

5.      Decrease the incidence of diverticulitis, colonic cancer, hemorrhoids.

Prevents the absorption of toxic component and carcinogens of diet in intestine.