Of course, when it comes to milk, there is that age old argument that human beings are the only mammal that is never weaned
Be that as it may ... there are some probiotics that are specially coated to survive the stomach (Primadophillus is one) and then there are some probiotics that are just totally different, like Primal Defense, that I can tell you for a fact DO make it to the intestines and, particularly for those of us with GI issues, they can really make a difference.
Digestive enzymes MUST help break the food down, else they'd never recommend them for folks with impaired digestion like those with cystic fibrosis. Doctors are pretty dense when it comes to this sort of stuff so something has to work undeniably before they recommend them
The bottom line IMO? The normal, healthy individual under the age of 40 probably doesn't need digestive enzymes, if you have a lot of indigestion, you need to look at your diet, but you should also be taking digestive enzymes with every meal. However, good probiotics are something we should all keep on hand. Every so often I'll put my husband and myself on a cycle of probiotics in addition to primal defense, which we take every day.
Alternative medicine has a theory that disease begins in the intestines, and it goes further than just regular elimination, but even that our immune system is based OUT of our guts, interesting concept ...