They say that over a long course of time with the right diet of mostly raw organic foods, you will clean out your system eventually. There are people who have fasted (I think there was a SWF (Salt-Water-Flush) faster who passed a few) with no PB that passed MP as well. Just stirring the pot with what I gathered from research and these forums... that is if you wish to believe everything you read rather then testing it yourself and figuring your own body out. ;)
But, as with everything in life, there will always be 2 sides to a coin.