Avoid toxic foods. Avoid sugars, fried foods, vegatable oils like canola & soy, meats that are cured wth nitrates & nitrites, aspartame, splenda, partially hydrogenated vegetable oils, maragarine, soy based products, sweetened beverages like juice & soda, microwaved foods, artificial colors & flavors. All of these products cause damage to the cells, tissues & organs in your body contributing to various diseases.
1. Diet modification of bowel diseases has not been well studied. However some general guidelines apply. High fiber, low red meat diet is helpful for good colon health low fodmap diet (google this and you will see the food to avoid) is considered to help irritable bowel syndrome symptoms.