Fiber and the Digestive System

Publication Number 348-835, Posted August 2001

1. DIGESTION BEGINS IN THE MOUTH.
   Fiber in food requires extra chewing which releases saliva. The breakdown of starches begin. Saliva helps clean the teeth.

2. FOOD PARTICLES PASS THROUGH THE ESOPHAGUS TO THE STOMACH.
   Here the food is mixed with digestive juices and is held until the small intestine is ready to receive and process. Fiber can absorb water here.

3. THE SMALL INTESTINE DOES THE MAIN WORK OF DIGESTION.
   Food is further broken down into small units which can be absorbed into the walls of the small intestine. The moisture that is in fiber adds weight that helps undigested particles move to large intestines.

4. THE LARGE INTESTINE RECEIVES THE UNDIGESTIBLE PARTICLES TO BE EXPELLED FROM THE BODY.
   After eating high fiber meals and snacks, these particles are soft, bulky and contain water making it easier for the body to release waste.

The main part of the digestive system is a hollow tube called the gastrointestinal (GI) tract. Food is moved through the GI tract by rhythmic waves of muscular action.

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