Betaine HCl is just used to increase the acidity of the stomach. This is important because in order for protein to break down, you have to have a low PH in the stomach. If it's too high, enzymes that break down the protein do not function properly, and also the stomach empties sooner. This is bad because then your stomach passes on protein that is not fully digested. This is a problem because your intestines are not supposed to break down protein, and the protein can then putrify in the gut causing gas and also increasing the toxic load on the liver. This is why many people say they get gas when they eat a "high protein diet." The reality is, their digestion sucks ass and they're not digesting the meat or whatever they're eating, and it just putrifies in their gut and gives them gas. Supplementing with Betaine HCl with meat SHOULD reduce problems such as this.
Pepsin, protease, etc, are just enzymes that help digest protein. Taken on an empty stomach, protease supposedly can reduce inflamation from injuries or DOMS. But it will also help improve digestion of meats, especially well cooked meats such as pot roast.
You should be able to find betaine HCl and broad-band enzymes almost anywhere. This is extremely beneficial if you have low stomach acid production, which could be a result of stress (cortisol erodes the lining of the stomach), meds and OTC meds, and poor nutrition. Often times it is a combination of all of these. Atheletes are notoriously deficient in zinc, and a zinc deficiency hinders stomach acid production! And the really bad part is reduced stomach acid decreases absorption of nutritents, leading to even MORE deficiencies and even MORE problems.
So without proper digestion, you will have a difficult time reaching almost ANY goal you have. And basically, any food that is not digested literally becomes a poison that your body has to deal with (read stress your liver).
Here is a link that you might find informative:
http://www.charlespoliquin.net/women/tips-display.cfm?WomenTipsID=16
