Yes they have been seen from liver surgeries and cadaver dissections. Scientists have been studying this for some time actually. There are actually some doctors that are advocates for the cleanse. These are mostly the older, smarter, and retired docs who don't need to make anymore money off of you. I have seen little evidence of current practitioners telling people to use this, probably because it means there's a chance you can improve your overall health (AND LESS NEED TO SEE A DOCTOR) without their help, meaning less money for them.