I believe that Robb is right, and you really shouldn't have a problem with long term production of your body's own digestive enzymes. On the contrary, I have read that it can actually help your body because having to produce all of its own enzymes for a long period of time can be draining on the production and lead to a decrease in production of enzymes. Not only thins, but there are many naturally occurring enzymes in the foods you eat, such as papaya and pineapple. So it is completely healthy and natural to take in additional enzymes to help your body digest. The supplement I use, Digestive Enhancement
(along with many other enzyme supplements out there), actually use the enzymes found in both papayas and pineapples...you just get a higher and more effective concentration of them.