Autoimmune Gastritis (Stomach) Causes, Signs and Symptoms

Gastritis is the term for inflammation of the stomach. As a hollow sac, it is the walls of the stomach that are inflamed to varying degrees. This may sometimes be isolated to the superficial inner lining of the stomach (mucosa) or it can extend through the entire wall of the stomach. Persistent inflammation leads to ulcers, which can be deep or shallow. Most cases of chronic gastritis are due to H.pylori (Helicobacter pylori) infection or the excessive and/or long term use of NSAIDs (non-steroidal anti-inflammatory drugs). However, a minority of chronic gastritis cases are not due external factors but arises with an immune-mediated reaction and is known as autoimmune gastritis. It needs to be considered as a possible cause of chronic gastritis that is not associated with H.pylori infection or NSAID use.

What is autoimmune gastritis?

Autoimmune gastritis is a type of chronic stomach inflammation due to the action of the immune system against stomach tissue and its components. It causes destruction of the stomach tissue with progressive atrophy of the stomach and is therefore also referred to as autoimmune atrophic gastritis or autoimmune metaplastic atrophic gastritis. Autoimmune gastritis leads to low gastric acid secretion (achlorhydria) and pernicious anemia (megaloblastic anemia) due to vitamin B12 deficiency and it is a known risk factor for gastric cancer.

The stomach is the first major organ of digestion lying between the esophagus and duodenum of the small intestine. There are three types of cells in the gastric wall – mucus, peptic and parietal cells. With regards to autoimmune gastritis, it is the parietal cells that are targeted by the immune system. These cells produce hydrochloric acid (HCl) and intrinsic factor (IF).

HCl is an important component of chemical digestion while intrinsic factor is needed for the absorption of vitamin B12. When the parietal cells are destroyed, the level of the substances it secretes are affected and this ultimately disrupts its respective roles in digestion and absorption. However, the other cells like peptic cells are also destroyed in the process although the immune system is not specifically directed at these cells in the way it is towards the parietal cells.

Pathophysiology of Autoimmune Gastritis

Antibodies are formed against the parietal cells, hydrogen-potassium ATPase (H+,K+-ATPase of the proton pump) and and intrinsic factor (autoantigens). These autoantibodies direct the immune response against this otherwise normal tissue and its components.  This reaction appears to be mediated specifically by the CD4+ T-cells. Most of the damage of the parietal cells arises in the body and fundus of the stomach while the antrum of the pylorus and cardia is spared entirely or at least to a very large degree.

Typically the inflammation and subsequent destruction and atrophy of the tissue is extensive. It usually affects the entire area but sometimes can be patchy with the isolated normal mucosa appearing like small nodules or polyps (pseudopolyps). As acid production drops with parietal cell destruction, the body tries to compensate by increasing the production and secretion of gastrin (digestive hormone). Usually gastrin stimulates gastric acid production by directly acting on the parietal cells and indirectly by acting on the enterochromaffin-like (ECL) cells. Hypergastrinemia (elevated blood levels of gastrin) continues to stimulate the ECL cells in autoimmune gastritis thereby causing it to increase in number (hyperplasia). The areas where atrophy occurs (fundus and body) may display abnormal cellular changes (metaplasia).

Causes of Autoimmune Gastritis

Autoimmune gastritis is mainly an inherited disorder. It is associated with many other hereditary conditions including Hashimoto thyroiditis, type I diabetes mellitus, Addison disease, primary hypoparathyroidism, Graves disease, myasthenia gravis, and Lambert-Eaton syndrome. However, the exact genes for autoimmune gastritis has yet to be identified. There also appears to be an association with chronic H.pylori infection but the exact link and mechanism is unclear. Other factors that need to be considered include long term use of proton pump inhibitors (PPIs) and gastrectomy (surgical removal of part of the stomach).

Signs and Symptoms of Autoimmune Gastritis

The clinical features are largely due to the pernicious anemia. While low gastric acid levels may affect digestion of several nutrients, it is usually minor if small portions of the gastric wall is affected. Instead the vitamin B12 deficiency is more prominent. The condition usually develops gradually and takes decades to reach a point where the deficiency causes significant clinical effects. The signs and symptoms in this regard may therefore include :

  • Abnormal sensations particularly in the legs (paresthesia) and numbness.
  • Smooth red tongue (glossitis).
  • Diarrhea.
  • Mouth pain (stomatodynia).
  • Cracking at the corner of the lips.
  • Weakness of the limbs.
  • Mild personality changes.
  • Poor memory.
  • Sometimes depression.
  • Malaise.

Please note that any information or feedback on this website is not intended to replace a consultation with a health care professional and will not constitute a medical diagnosis. By using this website and the comment service you agree to abide by the comment terms and conditions as outlined on this page

Ask a Doctor Online Now!
  • thx1104

    It looks like I have this. Almost everything hurts my stomach. Almost all supplements and vitamins aggravate my stomach pain. I can take a half dose of resveratrol once in a while. I’m just getting more and more ill and the doctors are helpless (hapless).

    • Hi Thx1104. Autoimmune gastritis is not as common a problem as other types like H.pylori gastritis. An upper GI endoscopy can help with the diagnosis along with other tests. Your doctor will be able to advise you further. It is best to see a gastroenterologist if possible.

      • thx1104

        I’ve tested negative for H. Pylori, and had a battery of tests. I’ve had ultrasonic endoscopy, MRI and CT scans. Immune boosting vitamins like B12 seem to feed my illness and cause more stomach pain. I’m trying Lion’s Mane right now to see if that can help me.

        • Hi Thx1104. It is quite interesting that there has been no conclusive diagnosis despite the battery of investigations. You mention herbal and nutritional supplements but do remember that these are not without side effects entirely, and can contribute to gastritis in some instances. Please do update us on your condition, if there is any improvement.

          • thx1104

            Well, the lion’s mane made me much worse … it seems to stimulate stomach acid production…. I had to take many tums over several hours. Some of these mushrooms are supposed to help with autoimmune disease, but so far, the one’s I’ve tried, exacerbate my stomach problems. (Mushrooms are high in B vitamins, so that could be part of the problem.) The next thing I might try is yeast derived Beta Glucan. Early stages of autoimmune atrophic gastritis are said to have HIGH stomach acid, while late stage has LOW stomach acid.

          • Amber

            Did you ever heal your stomach pain?

  • Lanna Barnett

    My gastroenterologist diagnosed me with autoimmune gastritis. He said that since there was no acid in my stomach I wouldn’t get stomach cancer. But this article said I am at high risk of stomach cancer. Which is it?

    • Hi Lanna. There is no way of saying that you cannot get stomach cancer simply because there is no stomach acid (more likely like low volume of stomach acid). There may have been some miscommunication or misunderstanding. We cannot advise you on your cancer risk as there are so many factors that can play a part. But as you can see from the article above, and as you will find in other medical sources, this type of gastritis may be associated with an increased risk of stomach cancer. You may further research it, especially with atrophic autoimmune gastritis. Here’s a link to a gastroenterology journal ( to help you with your research. However, we are not second guessing your specialist. He/she is in a better position to advise you further.

  • Johanna

    I was recently diagonsed with Autoimmune Atrophic Gastristis with negative H Pylori. Hence, weekly B-12 shot is necessary. The GI specialist was melochaly of giving me information of my condition. i.e. managment, do/don’ts, expectation, etc. All he said I have a small chance of stomach cancer. He was not able to give me information of what food to avoid, other symptons, and/or when to do follow up visit. He is the Chief of the Gastrology Departmen of a well know NYC Hospital.

    I accept my condition but would like to know what are the best managment for this ailment. He left me as I am on death row.


  • DrRob Kominiarek

    As a physician with Autoimmune Gastritis, traditional healthcare will leave you with many unanswered questions. Strongly recommend the following if diagnosed with AIG

    1. Have Cyrex panels 3,4,5,10 completed and eliminate all sensitive items as food choices
    2. Complete Spectracell Micronutrient profile so you can be strategic with supplements and not shotgun them
    3. Complete Adrenal function testing as AIG will slowly affect adrenal function whether you have antigens to 21-hydroxylase or not
    4. Complete comprehensive stool culture to identify potential pathogens/yeast to be eliminated and secretory IgA levels
    5. Complete genetic testing to determine if you should be taking methylcobalamin vs. hydroxycobalamin injections weekly
    6. Eliminate coffee, caffeine, tea, chocolate, gluten (even if gluten non-reactive), corn, soy, dairy, sugar, tomatoes, nightshades
    7. If still having food issues follow Autoimmune Paleo, read The Paleo Approach by Sarah Ballantyne, PhD
    8. Take charge of your health because none else will!

    All the Best!

    Dr. Rob Kominiarek
    ReNue Health