Do Enzymes Survive Digestion?

A common question regarding the effectiveness of supplemental enzymes is whether or not the enzymes survive the harsh conditions of the digestive tract. The argument is made that since enzymes are proteins, they will be digested by the stomach's proteolytic enzyme, pepsin, just as any other protein. Additionally, it is argued that the low acidity of the stomach will denature any undigested enzymes leaving them inactive.

In regards to the issue of digestion, this is a simple statement of fact. Enzymes are proteins that are digested just as any other protein, there is no special protective mechanism the shields enzymes from the action of pepsin. However, supplemental enzymes areshielded by the laws of probability. When enzymes are consumed with meals, the amount of protein in the food is so much greater then the chances of a pepsin molecule coming in direct contact with a molecule of supplemental enzymes.As a simple illustration, imagine a game of marbles. There are over one hundred marbles in the ring, most of which have a diameter of one inch, others have a half inch diameter and a very few have a 1/4 inch diameter. The marble you are shooting also has a 1/4 inch diameter. What size of marble are you most likely to hit? The one inch marbles are undigested food, the half inch marbles are partially digested food and the 1/4 inch marbles are enzymes. The smaller the molecule, the less likely it will be hit early in the game. Additionally, as digestion continues more and more mid-sized molecules are created increasing the total number of molecules that are available for contact. Thus enzymes are assured a high rate of survival during the stomach's proleolytic digestion.

The belief that stomach pH eliminates the benefits of supplemental enzymes is erroneous. First of all, a large percentage of the digestive activity of supplemental enzymes occurs in the upper region of the stomach where food may sit for as long as an hour before the digestive secretions mix into the food bolus. Secondly, research indicates that despite the pH of the digestive secretions being quite low (pH 1.0 - 1.5) that once mixed with the food, the environmental pH ranges from 2.5 to 5.0 dependent upon the foods consumed. With this food buffering system, the environment does not harmthe supplemental enzymes, in fact many function optimally under these conditions.