Protein Digestion in the Human Stomach.

Abstract

The primary function of the stomach being to digest protein, it would be desirable to be able to determine the actual accomplishment of the stomach in health and disease as far as protein digestion is concerned, instead of relying on acidity determinations as an indication. Determinations of the ratio of soluble to insoluble protein in gastric contents following a test meal might give useful information provided that the gastric contents remained a uniform suspension, and provided solid and liquid left the stomach at the same rate. On the other hand, if insoluble iron oxide were mixed with the flour and baked into the bread used as a test meal and if this oxide adhered to the undissolved portion of the gastric contents, the ratio of undissolved protein to iron would enable one to determine the percentage of protein of the test meal that had been put in solution by the gastric juice, and such a result would be fairly accurate whether or not there were stratification of gastric contents or selective evacuation of the stomach. This method should also provide a check on the significance of results of acidity determinations and of the use of the simple ratio of dissolved to undissolved protein in gastric contents.

Twenty-four normal men were given test meals consisting of 80 gm. of bread (made from flour containing 0.25% of red iron oxide) and 200 cc. of water. Twenty-five cc. portions of gastric contents were aspirated at 15 minute intervals (beginning at 30 minutes) until the stomach was empty. Determinations were made of dissolved protein (by centrifugation of contents and washing of the residue), of total protein, of undissolved protein, of iron, of pepsin and of free and total acidity.