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up to an hour. Here the salivary amylase continues to break down starches. Most food stays in the stomach two to four hours—less with a low-fat meal, more with a high-fat or high-fiber meal. When the stomach has finished its job, chyme (the mixture of food mash and gastric juices) has the consistency of split-pea soup. Over several hours it passes in small amounts through the pyloric valve into the duodenum, the first 12 inches of the small intestine. Chronic stress lengthens the amount of time that food stays in the stomach, while short-term stress usually shortens the emptying time. Most of us have experienced a nervous stomach, or a feeling in the pit of the stomach, or a stomach that feels like it’s filled with rocks.
    Once food enters your stomach, gentle mixing waves begin chopping up your food and increasing surface area. The hormone gastrin is also produced in the stomach and stimulates the production of gastric juices. Gastric juices are comprised of enzymes, hydrochloric acid, hormones, and intrinsic factor. For example, protein molecules are composed of chains of amino acids—up to 200 amino acids strung together. The stomach produces a hormone called pepsinogen. When pepsinogen is exposed to hydrochloric acid, it turns into pepsin, which begins protein digestion, breaking the protein you eat into short chains called peptides.
    Hydrochloric acid (HCl), produced by millions of parietal cells in the stomach lining, begins to break apart these protein chains. The parietal cells use huge amounts of ATP energy to concentrate acids to the low pH of about 1 that is required by the stomach. HCl also kills microbes that come in with food, protecting us against food poisoning, parasites, and bacterial infections. The hydrochloric acid in your stomach is so strong that it would burn your skin and clothing if spilled on you. Yet, the stomach is protected by a thick coating of mucus (mucopolysaccharides), which keeps the acid from burning through the stomach lining. When the mucous layer of the stomach breaks down, HCl burns a hole in the stomach lining, causing a gastric ulcer. Hydrochloric acid production is stimulated by the presence of gastrin, acetylcholine (a neurotransmitter), or histamine. The stomach also produces small amounts of lipase, enzymes that digest fat. Most foods are digested and absorbed farther down the gastrointestinal tract, but alcohol, water, and certain salts are absorbed directlyfrom the stomach into the bloodstream. That’s why we feel the effects of alcohol so quickly.
    Intrinsic factor is made in the stomach in the parietal cells, and it binds vitamin B 12 so that it can be readily absorbed in the intestines. Without adequate amounts of intrinsic factor, we do not utilize vitamin B 12 from our food, and pernicious anemia may occur. The main symptoms are dementia, depression, nervous system problems, muscle weakness, and fatigue. This is why many people benefit from vitamin B 12 injections, under a physician’s care, or use of sublingual B 12 or even B 12 in a nasal spray. I remember one elderly woman who had normal serum B 12 levels, but she felt enormously different when B 12 shots were added to her regimen. This simple, inexpensive therapy can dramatically affect quality of life for those who need it. By the time serum B 12 levels are low, your tissues are depleted of vitamin B 12 . A newer test to detect early B 12 deficiencies is called the methylmalonic acid test (MMA). Levels of methylmalonic acid rise when our bodies cannot transform vitamin B 12 to create energy. High levels of MMA indicate early B 12 insufficiency. Recently, researchers have remarked that probably the best test for B 12 is just taking sublingual B 12 supplements or a trial of B 12 shots to see if you feel better. I have seen this to be true; when people need B 12 and take it, their energy and sense of well-being soar. People who try B 12 and have sufficiency already don’t notice a thing.
    Hydrochloric acid is also