Hydrochloric Acid and Pepsin are secreted into the stomach to enable effective digestion. They are particularly critical to the digestion of proteins. Many factors can impair the production of hydrochloric acid, which is a very demanding task for the body. These may include: nutritional deficiencies, infections, stress, certain drugs, yeast infections and many others.

Adequate quantities of hydrochloric acid are essential for the absorption of many minerals and provides an acidic environment to prevent the passage of most bacteria into the body beyond the stomach. The correct pH (acidity) is also essential to activate many digestive enzymes that act upon food in the stomach and the intestines, this includes pepsin itself.