I did The Master Cleanse and did do the Shakes. They were very successful for me. When I'm not on the master cleanse, I don't use the psyllium husks, I go with the flax seed (highly benificial). I've read some colon cleansers that advertise that their's is safe for those that have problems with they psyllium. I'm not sure why the blood type does not like the psylium husks for o's, but the one thing I gather is on some people, the psyllium is abrasive on the stomach, or the psyllium "scratchs" on the way out. I would personally go for it during the cleanse, then avoid (not use daily) after that.(use flaxseed instead for daily usage) Let me know your success and good luck.