I have a habit of eating too much lean protein and not getting enough fiber. So things occasionally get hung up so to speak. The Heckman routine like LittleJim mentioned works. I have never done it for the full 30 days. But over the course of a week or two, it definitely gets things moving. I prefer it to chemical laxatives.
There is no empirical evidence that you can pull "toxins" out of your large intestine. But I have found the charcoal does keep the gas down.
Also, as far as the "Go Lightly" stuff the doctors give. Well, I have had cause to do that stuff twice...they lie. There is nothing lightly about that stuff. If you start taking that, better install seat belts on the thrown.