Avoid excess acid
Most foods in your stomach absorb and partially neutralize stomach acid. So, eating regular meals will help you prevent excess acid irritation and ulcers. Certain foods, however, irritate your stomach and should be avoided. Tobacco also stimulates acid production and weakens the stomach lining.

What about your intestines?
Your intestines have different requirements. In your small bowel, a large amount of residue (which eventually becomes feces slows the absorption of nutrients, which helps people with diabetes manage their sugar intake. It also dilutes irritating and harmful chemicals, reducing their ability to damage the lining of your bowel. High intestinal residue also increases your excretion of bile chemicals and thereby reduces your chance of having gallstones.

Your lower bowel functions best when full of the same soft, moist residue. The more bulk there is, the easier it can be passed along with the rhythmic squeezing called peristalsis. Low pressure inside your large bowel decreases your chance of getting diverticulosis.

The primary function of your lower bowel is to absorb water from its contents as it passes through. The longer stool remains in your large bowel, the drier it gets. And a dry stool is hard to pass, and leads to constipation. The lesson here is to drink extra liquids and to empty your bowels when the urge first presents itself.

Dietary residue
You can find dietary residue mainly in whole grains -- whole wheat, oats-- green vegetables, apples, pears, and commercial bulk laxatives like hemicelllose, bran, and psyllium preparations.