Yes absolutely, anything you run through the body is capable of straining the liver. Just like anything you lift is capable of straining your muscles. So you must always take care to start very small and build up gradually so as not to do more harm than good.
Slow and steady -- and consistent is the name of the game when it comes to cleansing. The thing I really like about the zeolite is that it kills a lot of birds with one stone. Rather than having to do something for each individual thing - this for the liver, that for the kidneys, this for the candida, that for the heavy metals, etc.
That can get expensive, time consuming and even be stressful on the body if done in excess -- and to top it off, it may not be getting down to the root of the problems.
In my opinion, nothing can take the place of colonics, liver flushes, eating well and I am beginning to think that zeolite belongs on that list as well.