When food enters the stomach, it is mixed with hydrochloric acid, pepsin and a host of other enzymes. The hydrochloric acid breaks down the food into a thick liquid mass called chyme. The peptic enzymes break down proteins into peptones, which are the building blocks for the amino acids. Many proteins are allergens, and will cause allergies, if they are not broken down by the acid and peptic enzymes. The peptic enzymes are most active in the conversion of proteins, when the pH strength of the stomach acid is at 1.0 to 1.3 pH. When the strength of the acid decreases the peptic enzymes convert less of the proteins into peptones. At pH 5.0 the peptic enzymes are no longer active in the conversion process. When this occurs raw unsterilized and converted proteins will enter the small bowel and cause allergic reactions. The strength of the acid also prevents the overgrowth of bacteria, and other pathogens in the digestive process. As part of the aging process, the stomach's acid producing cells, parietal cells, wane in their ability to produce sufficiently strong acid. This usually starts to occur in the 45 and up age groups, but it is not limited to any age group. When the stomach's parietal cells can no longer produce strong enough acid there is less sterilization of the nutrients and less conversion of proteins. This allows raw protein and nutrients to enter the small bowel, resulting in allergic reactions. The reduction in sterilization and conversion, is one of the main causes for developing allergies, as a person ages. Anyone that suffers from food allergies should get a pH diagnostic test. There is a low more information on the web, search for pH diagnostic test, pH capsule test, or pH gastrogram.