To natural health experts: what is the cheapest AND safest digestive cleanse?

I want to do a digestive cleanse that will dislodge any collected or undigested wastes left behind in my digestive. I have been having something that seems similar to a very mild "sprue" or malabsorption for at least 2 if not 3 months. So I figured that backed-up waste may be the issue. I dont’ really suffer from constipation, but do not take fiber as I used to do. I want to find the absolute cheapest BUT safest way to do it, possibly even using stuff around the house. Note: anyone who poo-poo’s (no pun intended! LOL) cleanses or any other natural health, please don’t respond.