I've done cleanses with Bentonite clay (and psyllium). I use Dr. Schulze 's produts. His "intestinal cleansing formula #2" is 95% Bentonite clay; and he suggests you mix it with juice, for flavor. He even says beer is ok! I think it tastes bearable with apple juice. Just get it down, mixed with liquid, then follow with a glass of pure water, so it doesn't clog in your throat/stomach passage-ways. Wash it down good!
Check out Dr. Schulze 's teachings,
or look him up here http://www.800herbdoc.com
If you feel sick during a cleanse, like flu symptoms, yes that is natural BUT not neccessarily healthy. From what I've learned, that doesn't mean you should speed up the cleansing process because you'r body can only eliminate so much at once. It takes time. Cleansing too fast CAN make you feel sick and if so that means your body is REABSORBING the toxins.
I read this in Linda Page's "Healthy Healing" book, which is excellent. www.healthyhealing.com