Back in '04 or '05, my doctor suggested i take Iodoral. Naturally, i started reading up on the stuff; as a result i ended up exploring this site and finding out about systemic enzymes, too. Sounded interesting, so i then had to start reading up on THOSE.
It seems that in Germany, back in the cold-war days, Eastern Bloc sports trainers were looking for a better way to control inflammation in their over-trained corps. Hearing of a Munich doctor/manufacturer who was getting good medical results from enzymes for inflammation, they managed to procure a large amount and started experimenting. To their surprise and delight, there were benefits above and beyond the immediate goal. More info here, if you're interested....
Systemic enzymes (designated so to distinguish them from digestive ones) have an application in not only fighting inflammation but in "eating" a lot of proteins which aren't beneficial to the body. Protein and fibrin coatings on viruses and cancer cells, excess scar tissue, debris in the bloodstream that clogs microcirculation, fibrosis that limits organ function, all this is controllable with enzyme use. They've been used in Europe and Japan for decades, but they still haven't widely caught on in this country.
The body, it turns out, makes a finite amount of enzymes in a lifetime, no matter how long it lasts. This fact could be used as an argument that all nature really wants us to do is survive till we reproduce, because at around the age of 27 our production of enzymes tapers off dramatically, to "keep" us as best they can on dwindling supplies. As an example within the experience of most people, compare the scars you get now to the ones you got as a child -- now they're thicker and less pliable, more unsightly. The logic goes, then, that supplementing the enzymes your body now doles out so scantily will help you heal and maintain functions like a younger person does.
When i started taking them, i felt like i was beginning to experience fibromyalgia, and i had carpel-tunnel symptoms when i did any sewing or crocheting -- these faded away. I've been curiously resistant to viruses since i began enzymes, too. A couple of years ago, the dog roughed up my thumb REAL GOOD, but i can only see the scar if i look very closely. I'm a believer.
I understand that systemic enzymes do great things for diabetics and cancer-sufferers as well as helping to keep viruses at bay. Of course, mainstream medicine pooh-poohs their use for anything but digestion. They claim that orally-administered enzymes won't live to reach the bloodstream, let alone pass the blood-brain barrier to aid a person with a brain tumor. As usual, they're wrong, because the latter has been documented to happen. Of course, to survive stomach acid, the supplement must have the "enteric" coating -- that's one reason why your brand of enzyme is important. The other big reason is, they have to be handled right; overheated enzymes are dead enzymes, and they won't help anybody.
I started out using a brand called Vitalzym, then when Dr. Wong came out with his own (stronger) version, i switched to Zymessence. Unfortunately, they BOTH changed their formulations, and i was about ready to dump the whole lot of them. :-P I'm happy to say, it wasn't necessary, because the lady at Quackcenter (a nurse with a PhD) had done her research and found someone who made a product that turned out to be identical to the ORIGINAL Vitalzym -- it's called Exclzyme -- and i'm contentedly taking that these days. Three caps in the morning a half an hour (at least) before anything else goes in my mouth.
Did i mention that in the last seven or eight years i've only had the flu once or twice, and very lightly? A lot of supplements and foods have done good things for me, but THAT i credit directly to the systemic enzymes.