STEMAcademiaAgriculture & FarmingHumanitiesSocial Sciences

Hydrochloric Acid in the Stomach and Digestive Problems

Updated on April 10, 2016
AliciaC profile image

Linda Crampton is a teacher with a first class honors degree in biology. She writes about human biology and the scientific basis of disease.

A stomach enzyme called pepsin needs an acidic environment in order to digest protein. Fish, meats, eggs, dairy and beans are all rich in protein.
A stomach enzyme called pepsin needs an acidic environment in order to digest protein. Fish, meats, eggs, dairy and beans are all rich in protein. | Source

Hydrochloric Acid in the Stomach

The inside of the stomach is a very acidic environment, especially after food has just been eaten. The acidic pH is created by hydrochloric acid, which is secreted by cells in the stomach lining. The acid is needed to activate a stomach enzyme that digests the proteins in food. Hydrochloric acid also kills many bacteria that enter the stomach, protecting us from harm.

Although stomach acid is a very helpful substance, we're normally unaware of its presence. The lining of the stomach is coated with mucus to protect it from acid damage. In addition, when the mixture of food and acid leaves the stomach and enters the small intestine, it's neutralized by the basic environment of the intestine. Sometimes, though, stomach acid causes problems, either because too much or too little is made or because it doesn't stay where it belongs.

A circular muscle called a sphincter closes the entrance to the stomach. If the sphincter doesn't work properly, food and acid may move up into the esophagus, creating a burning sensation. Stomach acid can also aggravate ulcers, making them more painful. Sometimes cells in the stomach lining are damaged by a factor other than an acid attack and are unable to make hydrochloric acid. Without enough acid, protein digestion in the stomach is difficult and bacterial overgrowth can occur.

Anatomy of the stomach
Anatomy of the stomach | Source

Functions of the Stomach

Hydrochloric acid plays an important role in food digestion. The acid is made by parietal cells in the stomach lining and does its job in the stomach cavity, or lumen. The parietal cells also secrete intrinsic factor, which is necessary in order for vitamin B12 to be absorbed in the small intestine.

Other stomach lining cells known as chief cells make a substance called pepsinogen. Hydrochloric acid converts pepsinogen into an enzyme called pepsin. Pepsin begins the digestion of protein in our food, breaking up the long, folded chains of amino acids into shorter and simpler structures. The enzyme requires an acidic environment to do its job. Enzymes in the small intestine complete the breakup of the protein molecules, allowing individual amino acids to enter the bloodstream.

The pH in the stomach varies. If a person hasn't eaten for a long time, the pH of stomach fluid is generally around 4. When food enters the stomach, hydrochloric acid production increases and the pH may fall to as low as 1 or 2, a very acidic condition. Components of the food often raise the pH slightly as digestion proceeds. The acid not only provides a suitable environment for pepsin to work but also kills many potentially harmful microbes that enter the stomach in our food.

The parietal and chief cells are located in gastric glands in the stomach lining. The glands secrete a liquid called gastric juice. Around 2 to 3 litres of this liquid are secreted each day. Gastric juice contains water, a protein called mucin, hydrochloric acid, pepsinogen, intrinsic factor and other chemicals.

The Digestive Tract

In acid reflux and GERD, acidic stomach contents move up from the stomach into the esophagus.
In acid reflux and GERD, acidic stomach contents move up from the stomach into the esophagus. | Source

Making Hydrochloric Acid - The Proton Pump

The production and secretion of hydrochloric acid is a complex process. A major contributor to the process is a proton pump in the membrane of the parietal cells. A proton pump is a special protein inside a membrane, which is either the cell membrane or the membrane of an organelle in the cell. The protein transports protons across the membrane by active transport, a process that requires energy.

A hydrogen atom is made of a positively charged proton and a negatively charged electron. When the atom loses its electron to form a hydrogen ion, all that remains is a proton. A hydrogen ion (H+) is therefore the same thing as a proton.

Hydrogen ions are moved through the membrane of a parietal cell and into the duct of a gastric gland by a proton pump known as H+/K+ ATPase. Chloride ions (Cl-) move through the parietal cell membrane by diffusion, a process that doesn't require a protein carrier or added energy. The hydrogen ions and chloride ions join in the duct of the gastric gland to make hydrochloric acid. The video below shows the process in more detail.

The Proton Pump in the Parietal (Oxyntic) Cells of the Stomach

Acid Reflux and GERD

The entrance to the stomach is protected by the lower esophageal sphincter, or LES. A sphincter is a circular muscle that closes or opens the entrance or exit of a tubular structure. Under normal circumstances, the LES closes the entrance to the stomach once food has entered its lumen. If the LES doesn't close or if it opens while food is still in the stomach, the churning, acidic mix in the stomach may be pushed up into the esophagus. The hydrochloric acid irritates the wall of the esophagus, producing pain and a condition known as heartburn. There may also be a sour taste in the mouth.

Acid reflux and GERD (gastroesophageal reflux disease) are closely related conditions, but GERD is more serious than acid reflux. Many people experience acid reflux occasionally. In GERD, the reflux is experienced regularly. The regurgitated acid produces heartburn, a sour taste and sometimes additional symptoms, including coughing, wheezing, chest pain and difficulty in swallowing.

GERD requires medical treatment. If the esophagus is exposed to acid frequently over a long period of time, its lining may be damaged by the acid. This can lead to further health problems, which may be serious.

Helicobacter pylori, the cause of most stomach ulcers
Helicobacter pylori, the cause of most stomach ulcers | Source

Stomach Ulcers, H. pylori and Acid

An ulcer is a sore on the stomach lining. Ulcers in the stomach are known as stomach, gastric or peptic ulcers.

It used to be thought that a person under stress produced excess stomach acid and that this acid damaged the stomach lining and caused an ulcer. It's now known that stomach ulcers are usually caused by a bacterium called Helicobacter pylori, or H. pylori. They may also be caused by long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs), which reduce the amount of protective mucus made in the stomach. Aspirin is an NSAID. Although stomach acid doesn't cause an ulcer, it often makes it more painful.

H. pylori is an interesting creature, even though it may cause pain. It evades the acid that kills most bacteria and lives in the mucus coating on the stomach lining. Strangely, in some people the bacterium lives harmlessly in the digestive tract while in others it causes stomach ulcers or inflammation of the stomach lining (gastritis).

Antacids may provide temporary relief from stomach problems, but if someone needs to take lots of antacids they should visit a doctor
Antacids may provide temporary relief from stomach problems, but if someone needs to take lots of antacids they should visit a doctor | Source

Medications for Reducing Stomach Acid

Doctors usually treat an H. pylori infection by prescribing antibiotics as well as medications that suppress acid production in the stomach. The most popular medication is a type known as a proton pump inhibitor, which blocks the production of hydrochloric acid. It joins to the protein pump, preventing the pump from attaching to hydrogen ions and transporting them to the duct of the gastric gland.

Sometimes other types of drugs called H2-receptor antagonists are prescribed to reduce the acid level in the stomach. These drugs block the receptor on the parietal cell membrane that normally binds to histamine. Histamine joins to parietal cells to trigger the process that makes hydrochloric acid. Proton pump inhibitors and H2-receptor antagonists are also prescribed for people who suffer from GERD.

Proton pump inhibitors are powerful reducers of stomach acid and are popular medications. They are often prescribed instead of H2-receptor antagonists because they are thought to be more effective, but their long-term use may increase the risk of osteoporosis and bone fractures. A limited amount of evidence suggests that proton pump inhibitors may block hydrogen ion transport in the bones as well as the stomach.

Some people take simple antacids to neutralize the acidity in their stomach. These aren't as effective as the more modern drugs because they don't prevent the acid from being made. They can provide quick, temporary relief from a mild case of acid reflux or pain caused by acid in the stomach, but anyone who finds themselves repeatedly taking antacids needs to visit a doctor for a diagnosis and treatment.

In some places, proton pump inhibitors and H2-receptor antagonists are sold over the counter without a prescription. If someone is tempted to use these because antacids aren't working, it's very important that they see a doctor to get his or her advice instead of performing self-treatment.

How a Proton Pump Inhibitor Works

Hypochlorhydria and Achlorhydria

Significant hypochlorhydria (low stomach acid) seems to be more common in elderly people than in younger people. Some evidence suggests that medications that are designed to reduce acid production in the stomach may cause hypochlorhydria. In severe cases, acid production stops and the condition is called achlorhydria.

Chronic hypochlorhydria may reduce bone density. A low level of hydrochloric acid in the stomach cavity can lead to an overgrowth of bacteria, including Helicobacter pylori. The bacteria may travel into the small intestine, where most nutrient absorption takes place. Here they may compete with human cells for the absorption of nutrients, including the calcium and other minerals needed to make strong, dense bones.

Without activated pepsin in the stomach, food containing protein will pass into the small intestine undigested. An enzyme called trypsin is present in the small intestine after we eat and does the same job as pepsin. Other enzymes in the small intestine complete the digestion of proteins into individual amino acids, which are then absorbed into the bloodstream. Nevertheless, without the action of pepsin, digestion may be reduced.

Symptoms of low stomach acid include stomach discomfort and bloating. Nausea and vomiting may also be present. In addition, there may be reflux through the lower esophageal sphincter. A doctor should be consulted if these symptoms are present, since they can indicate different disorders.

A red blood cell, an activated platelet and a white blood cell: vitamin B12 is needed to make red blood cells
A red blood cell, an activated platelet and a white blood cell: vitamin B12 is needed to make red blood cells | Source

Autoimmune Atrophic Gastritis in the Stomach

There are many possible causes of gastritis, or inflammation of the stomach lining. These include the presence of H. pylori and the overuse of NSAIDs. Inflammation of the stomach lining is sometimes due to an autoimmune disorder. In this type of disorder, the immune system attacks and destroys the body's own cells.

Autoimmune atrophic gastritis is an "atrophic" disease because tissue is lost. The immune system damages the cells in the stomach lining, including the parietal cells and the chief cells. As a result, the amount of hydrochloric acid secreted decreases. In a serious case of gastritis the secretion may end altogether.

Autoimmune gastritis also reduces the amount of intrinsic factor secreted by the parietal cells, which in turn reduces the amount of vitamin B12 that can be absorbed. Vitamin B12 is needed to make red blood cells. The decrease in the vitamin B12 level may lead to a condition called pernicious anemia. The disease can be serious if it's untreated, since our body needs red blood cells to stay alive. Luckily, vitamin B12 injections can provide a person with the missing nutrient.

Red blood cells transport oxygen to the body cells. The cells need the oxygen in order to make use of food.
Red blood cells transport oxygen to the body cells. The cells need the oxygen in order to make use of food. | Source

Hydrochloric Acid at Work

Like the myriad of other processes that occur in the amazing human body, hydrochloric acid production and action generally occur as required and without our awareness. Unfortunately, sometimes people are aware of the effects of too much or too little acid in the stomach. Luckily, there are ways to relieve or help these conditions, although a doctor's aid may be required.

References and Further Reading

© 2013 Linda Crampton

Comments

    0 of 8192 characters used
    Post Comment

    • AliciaC profile image
      Author

      Linda Crampton 8 days ago from British Columbia, Canada

      Thank you, Juma.

    • profile image

      Juma 9 days ago

      Thank you very much

    • AliciaC profile image
      Author

      Linda Crampton 11 days ago from British Columbia, Canada

      Thank you very much, Janice.

    • profile image

      Janice 12 days ago

      One of the best articles I have read, and I have read many about this subject. Well done Linda.

    • AliciaC profile image
      Author

      Linda Crampton 12 days ago from British Columbia, Canada

      I appreciate your comment.

    • profile image

      Great article 12 days ago

      Thanks Linda

    • AliciaC profile image
      Author

      Linda Crampton 3 weeks ago from British Columbia, Canada

      There's a condition called laryngopharyngeal reflux in which acid from the stomach gets into the throat and larynx. The affected person sometimes feels like they have mucus in their throat. You should seek a doctor's advice if you're experiencing a mucus problem.

    • profile image

      Char 5 weeks ago

      Can mucous backing up into the throat be a sign of low stomach acid?

    • AliciaC profile image
      Author

      Linda Crampton 6 weeks ago from British Columbia, Canada

      This is not a generally accepted idea. Doctors often prescribe proton pump inhibitors for excess stomach acid.

    • profile image

      Digestive Flora 7 weeks ago

      Proton Pump Inhibitors are a no no in fixing acid reflux problems. The problem really comes from TOO LITTLE stomach acid. More acid production is the key.

    • AliciaC profile image
      Author

      Linda Crampton 2 months ago from British Columbia, Canada

      Hi, Fehzab. Thanks for the comment. You may be thinking of gastritis, which is inflammation of the stomach lining.

    • AliciaC profile image
      Author

      Linda Crampton 4 months ago from British Columbia, Canada

      You should visit your doctor and ask him or her about this problem, Jasvir. You need a physician's advice.

    • profile image

      Jasvir Singh Bariyal 4 months ago

      Sometimes when I have suffered from acidity. A very large amount of acid reverse into my food pipe and it attack on my neck (Larynx) perhaps and which cause difficult in swallowing and have smell like burning all the day.what should I do?

    • AliciaC profile image
      Author

      Linda Crampton 5 months ago from British Columbia, Canada

      Hi, J.O. I'm sorry about your health problems and the fact that you haven't found an explanation for the ulcers. If the possible causes listed in this article don't apply, I think it's best if you consult a doctor. A physician should be able to give you advice about your specific situation, although from what you say it looks like it might take a while to get an explanation. I hope you find an answer soon. The situation must be frustrating for you.

    • profile image

      J.O 5 months ago

      How is it possible for stomach ulcers to form in the duodenum etc, if one has been tested for H.Pylori and received a negative result? I have had esophageal pH monitoring, gastroscopy, upper GI series etc and have been loosely diagnosed with a probably type of IBS, but no strict diagnosis. I have ulcers however they were said not to be caused by H.Pylori, what are some other possible causes?

    • AliciaC profile image
      Author

      Linda Crampton 6 months ago from British Columbia, Canada

      Thank you very much, Kohl.

    • profile image

      Kohl 6 months ago

      .... I have a bookmark folder of just your articles and i just realized wow please keep up the amazing work

    • AliciaC profile image
      Author

      Linda Crampton 6 months ago from British Columbia, Canada

      Hi, Nna. There are medical tests that a doctor can perform to determine the amount of acid in the stomach. You might want to talk to your doctor about the advisability of getting one of these tests. Doctors can also perform a variety of tests to help them diagnose pernicious anemia.

    • profile image

      Nna 6 months ago

      How do you know that the amount of acid is enough? What happens if it is all gone? How do you know that? I just found out this month I have autoimmune atrophic gastritis. Also have alpha thalesemia. In Dec, I was very low in iron, so took pills. Drs thought it was low iron due to thalesemia but how do I know it wasn't pernicious anemia?

    • AliciaC profile image
      Author

      Linda Crampton 7 months ago from British Columbia, Canada

      I'm not a doctor, Genie, but I suspect that your self-treatment could backfire. I think that it's important that you consult your physician to find out what's happening in your digestion system. If for some reason this consultation doesn't help you, you might want to see a different doctor.

    • profile image

      Genie 7 months ago

      I have been taking Hydrochloride acid prior to meals for months. Acid reducers were not helping the burning in my throat and stomach discomfort. I have reflux that hasn't been identified, I know it is not Acid!

      I feel better, could this backfire?

    • AliciaC profile image
      Author

      Linda Crampton 3 years ago from British Columbia, Canada

      Crafty, I'm very sorry about all your stomach problems. I very much hope that you find the cause of your gastritis and a solution to the problems that you're having. Thank you for the comment. I know that you're having a difficult time right now, but I hope your Christmas is as happy as possible.

    • CraftytotheCore profile image

      CraftytotheCore 3 years ago

      I truly found this educational, informative, and interesting. I was diagnosed with gastritis recently. I have suffered from stomach issues since the beginning of this year. I went to a few emergency rooms with horrific pain and eventually discovered through various testing that I have gastritis, and my gallbladder had to be removed. I ended up in a hospital this past spring with heart issues....which turned out to be something to do with my asthma and lungs. Anyway, one question remains is why do I have gastritis. I took nexium for some time. But then I stopped eating gluten and soy. I am doing better overall, but I still suffer with stomach pain at night. And I can no longer eat tomatoes at all because the acid hurts.

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you very much, wabash annie! I appreciate your comment.

    • wabash annie profile image

      wabash annie 4 years ago from Colorado Front Range

      I really found this Hub interesting and the pictures/diagrams helped as I am visual. I intend to read it over a couple of times more. Thanks for writing it!!

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you for the comment and the votes, Crystal. I'm sorry about your digestive problems!

    • Crystal Tatum profile image

      Crystal Tatum 4 years ago from Georgia

      Well, this is a bit over my head, but I relate to it through experience, if not intellectually. I've had a lot of digestive problems. Great job! Voted up and interesting

      .

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you so much for the visit and the lovely comment, Peggy. I appreciate all the votes and the share as well.

    • Peggy W profile image

      Peggy Woods 4 years ago from Houston, Texas

      You do such a great job with these health related hubs Alicia. This one should be of interest to many people who know or who suffer from some of these maladies caused by too much or too little hydrochloric acid in the stomach. You took us from A to Z with this hub. It was not that many years ago that doctors realized the cause of ulcers and began treating it with antibiotics. Medical learning keeps advancing and treatments are altered with the times. It is a fascinating subject. Up, useful and interesting votes and will share. Thanks for all the hard work you put into this hub.

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you very much for the comment and the vote, drbj. I appreciate them both!

    • drbj profile image

      drbj and sherry 4 years ago from south Florida

      Very thorough as usual, Alicia. The videos are especially revealing. Thank you for all your time and excellent effort. Voted Up.

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you, Prasetio. I appreciate your comment and visit!

    • prasetio30 profile image

      prasetio30 4 years ago from malang-indonesia

      Once again...I learn something new related with stomach and digestive problem. Good job, Alicia. You always brought many knowledges here, especially for health. Voted up and take care!

      Prasetio

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you very much, Deb. It is strange that some people don't get ulcers even when they have a Helicobacter infection. It would be very interesting to know why!

    • aviannovice profile image

      Deb Hirt 4 years ago from Stillwater, OK

      Fantastic work. My mother had ulcers when I was growing up, and she popped tums, etc. like crazy. I eat loads of spicy foods, and have never been bothered by such things, so I suppose that I am lucky.

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Bill. It sounds like you have a great immune system! Thank you very much for the visit and comment.

    • billybuc profile image

      Bill Holland 4 years ago from Olympia, WA

      You know, Alicia, I read hubs like this one, and others on the subject of health, and I realize just how lucky and blessed I am. I am a very healthy person; never had any major health problems...rarely even have the flu. Great DNA, wherever it came from. :) thanks for the information