Beleive it or not I know Chiropractors that have had their gallbladder removed. And chiropractors mates.
The problem with Natural Healing is it's not very scientific. The application of some of it is very technical but the priciples are common everyday priciples every machine operates on.
Can't do a scientific double blind study on unplugging the kitchen sink. Just unplug the damn thing. Of course that applies to the colon and liver. The two organs that provide a clean nutritious environment for the cells to live in.