We already know that fibrous food, basically fruits and vegetables, are natural colon cleansers. People, however, do not eat enough of it. Or they just eat food like corn and papaya if they want to facilitate bowel movement for the day, which is still not colon cleansing.
To avoid colorectal cancer as well as other colon-related problems, meat has to be avoided. You can start by eating smaller portions if you're used to eating lots of it. Then start skipping meals with meat, or skipping days. Alternate days of meat intake until you reach a point where you can go for days without it, or just use a little of it to flavor dishes on occasion.
Not only do you avoid colon problems this way and facilitate your movement, you also benefit from the nutrition vegetables and fruits bring. You also avoid hormones used on meat products and possibly a lot of preservatives as well.