Re: do digestive enzymes work
I'm going to agree with janewhite1 that digestive enzymes are generally not needed. I don't know though, because I'm no expert on this stuff, but it just seems that unless you have some serious deficiency, digestive enzymes probably wouldn't be needed as a supplement.
As far as your statement about "synthetic enzymes" there really isn't any such thing. Enzymes are usually produced the same way from natural foods. For instance, nattokinase is produced in soybean fermentation. It just so happens that they then freeze-dry the enzymes and put them in a capsule. They are still natural, however.
And, yes your body does absorb them. Systemic enzymes are readily absorbed by the body, which can include amylase, bromelain, papase, serrapeptidase, trypsin, chymotrypsin, etc.
There is a LOT of enzyme research out there, so I recommend checking it out.