By Ben Fuchs | Pharmacist Ben
What is the importance of stomach acid? According to an article in USA Today, Americans spend almost a billion dollars annually on over-the counter acids and over 13 billion dollars on the prescription varieties. Despite these facts, according to many health care practitioners, deficiencies in stomach acid production is a more significant problem than hyper-secretion.
A little known but vital consideration is the importance of having enough stomach acid. The stomach is supposed to secrete acid to break down food into a soupy consistency called chyme. Acidification of food is required for absorption of key nutrients as well as to stimulate digestive juices from the pancreas and gall bladder.
Regular antacid use can impair both the normal digestive process and is associated with numerous health symptoms such as osteoporosis and hip fractures, malabsorption of critical nutrients like selenium, iron, and vitamins A, E, and the B-complex. And it may actually cause an increase in stomach acid production known as acid rebound.
By Adam L. VanWert, Pharm.D., Ph.D. (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
Gastric acid, gastric juice or stomach acid, is a digestive fluid formed in the stomach and is composed of hydrochloric acid (HCl), potassium chloride (KCl) and sodium chloride (NaCl). The acid plays a key role in digestion of proteins, by activating digestive enzymes, and making ingested proteins unravel so that digestive enzymes break down the long chains of amino acids. Gastric acid is produced by cells in the lining of the stomach, which are coupled in feedback systems to increase acid production when needed. Other cells in the stomach produce bicarbonate, a base, to buffer the fluid, ensuring that it does not become too acidic. These cells also produce mucus, which forms a viscous physical barrier to prevent gastric acid from damaging the stomach. The pancreas further produces large amounts of bicarbonate and secretes bicarbonate through the pancreatic duct to the duodenum to completely neutralize any gastric acid that passes further down into the digestive tract.
The main constituent of gastric acid is hydrochloric acid which is produced by parietal cells (also called oxyntic cells) in the gastric glands in the stomach. Its secretion is a complex and relatively energetically expensive process. Parietal cells contain an extensive secretory network (called canaliculi) from which the hydrochloric acid is secreted into the lumen of the stomach. The pH of gastric acid is 1.5 to 3.5[1] in the human stomach lumen, the acidity being maintained by the proton pump H+/K+ ATPase. The parietal cell releases bicarbonate into the bloodstream in the process, which causes a temporary rise of pH in the blood, known as an alkaline tide.
The highly acidic environment in the stomach lumen causes proteins from food to lose their characteristic folded structure (or denature). This exposes the protein’s peptide bonds. The gastric chief cells of the stomach secrete enzymes for protein breakdown (inactive pepsinogen, and in infancy rennin). Hydrochloric acid activates pepsinogen into the enzyme pepsin, which then helps digestion by breaking the bonds linking amino acids, a process known as proteolysis. In addition, many microorganisms have their growth inhibited by such an acidic environment, which is helpful to prevent infection.
