Reddit mentions of Dr. Jensen's Guide to Better Bowel Care: A Complete Program for Tissue Cleansing through Bowel Management

OK. First things first, the theory behind those cleanses has been proven false in the modern era because of colonoscopy. Most of those books were written decades ago and have been reprinted for a half century or more.

My ex was a big fan of hosing out her insides, and she had all the books that dealt with that subject. She was also a big fan of hosing out my butt any time I'd come down with a cold or illness which personally added to my discomfort.

If you think your bowel movements are irregular, I recommend picking up a loaf of Ezekial 4:9 bread from the supermarket (look in the frozen health food area, but if your supermarket lacks it, pretty much any health food store large enough to have a freezer will carry it). Eat no more than 2 slices of bread, and do not toast it (that seems to burn the fiber). It is extremely high in fiber and will get you back to regular in less than 12 hours.