Dietary fiber can be soluble (able to dissolve in water) or insoluble. Fiber cannot be digested. However, soluble fiber is fermented by bacteria in the digestive tract, and absorbs water to become a gelatinous substance. Insoluble fiber has bulking action but is mostly not fermentated.( 7

Chemically, dietary fiber consists of non-starch polysaccharides such as cellulose and many other plant components such as dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans and oligosaccharides.

The natural physician’s healing therapies, Mark Stengler,N.D. 2008)

Websites:

7.http://en.wikipedia.org/wiki/Dietary_fiber#cite_note-Anderson-1#cite_note-Anderson-1