Many of us HM toxic folks need digestive enzymes. Cutler writes that Hg mess with them.
Some people need more of a particular enzyme. For example I have a need for more protease for high protein meals. My sister and a close friend seem to need more amylase for dealing with certain vegatables--peppers, onion, etc. I've heard of some who need more lipase for dealing with fats. there are others for dealing with milk, gluten, etc.