no you can't juice an avocado, you can make a smoothie out of it, but you will digest taht and you won't be juice fasting at that point.

some good colon cleansing juices are beet, pineapple, ginger, and wheatgrass. i am not surea bout liver, apple is good. dazzle has a lot of great info on what produce is good for different things, you might want to check out her blog it is very good with lot of info.

ff