Autoimmune Gastritis: Symptoms, Causes, & Gut-First Treatment

• What Is Autoimmune Gastritis|
• Symptoms|
• Causes|
• Diagnosis|
• The Role of Gut Health & Leaky Gut|
• Treatments|

Autoimmune gastritis is a relatively rare condition, but it often flies under the radar because its symptoms can be vague and easy to miss. Maybe you’ve felt nauseous after meals, chalked it up to a sensitive stomach, and moved on. Or you notice mild upper-abdominal discomfort, feel full after just a few bites, or battle a level of fatigue that never really improves. You might even have tingling or “pins and needles” sensations in your hands or feet.

On their own, these symptoms are easy to blame on stress, aging, irritable bowel syndrome (IBS), or simply your “normal.” But when they show up together, they can point to something more specific—autoimmune gastritis.

That space between knowing something is off and finally having a name for it can be incredibly frustrating. The upside is that once autoimmune gastritis is identified and you’re following a plan that supports stomach function and nutrient absorption, it can usually be managed very well.

What Is Autoimmune Gastritis?

Autoimmune gastritis (AIG), also known as autoimmune metaplastic atrophic gastritis, is a condition where the immune system mistakenly targets the stomach lining.  Normally, your immune system makes antibodies to attack things that don’t belong, like bacteria and viruses. But in autoimmune disorders, the immune system loses the ability to distinguish “self” from “other” and begins to attack healthy tissues. 

With AIG, the immune system targets the parietal cells in the stomach lining (also called the gastric mucosa). Parietal cells are responsible for making stomach acid (also called hydrochloric acid), so when they’re damaged, stomach acid drops. Low stomach acid can make it hard to absorb certain nutrients, including iron, which is why iron deficiency anemia can be an early finding in AIG 1.

AIG can also involve antibodies that attack a stomach protein called intrinsic factor. Intrinsic factor is what allows you to absorb vitamin B12, a nutrient that’s essential for healthy nerves and strong red blood cells. Without enough intrinsic factor, B12 levels can drop over time, which can affect nerve function and healthy red blood cell production 1. 

If left untreated, ongoing vitamin B12 deficiency can lead to pernicious anemia, which may cause symptoms like crippling fatigue, nerve problems, heart palpitations, indigestion, and weight loss from a lack of appetite 2. 

Over time, autoimmune gastritis can also cause the lining in the stomach and upper part of the intestines to thin (a medical condition called atrophic gastritis). Atrophic gastritis increases the risk‌ of developing intestinal metaplasia (abnormal cell growth) or hyperplasia (too much cell growth) in the intestinal lining 3.

Symptoms of Autoimmune Gastritis

AIG can be hard to diagnose because it often goes without noticeable symptoms beyond subtle stomach discomfort. In fact, up to 30% of AIG patients have no symptoms when they are first diagnosed 4. The most common signs of AIG are iron deficiency anemia and pernicious anemia (anemia caused by B-12 deficiency) 5. Common signs and symptoms of AIG include:

• Chronic indigestion (also called dyspepsia) 5
• Nausea 5
• Feeling overly full after eating, even small amounts 5
• Weight loss 5
• Iron deficiency anemia 5 
• Vitamin B-12 deficiency 5
• Feeling tired often (caused by iron and B-12 deficiency) 1
• Restless leg syndrome (caused by iron deficiency) 1
• Shortness of breath and feeling lightheaded (caused by iron deficiency) 1

Rarer signs and symptoms of AIG include high homocysteine (a type of protein that, when elevated, can harm heart health), infertility, and miscarriages 5. 

Decreased stomach acid increases the risk of Helicobacter pylori infection in people with AIG. In turn, H. pylori is a risk factor for a type of stomach tumor called gastric adenocarcinoma and peptic ulcers 6. 

Autoimmune gastritis often coexists with other autoimmune diseases. These include  7:

• Hashimoto’s thyroiditis
• Type-1 diabetes mellitus
• Crohn’s disease
• Addison’s disease
• Vitiligo

Because autoimmune gastritis is a progressive condition, long-term complications can include neuroendocrine tumors and stomach cancer. Endoscopic monitoring may be recommended to screen for these developments, especially in high-risk individuals 4.

What Causes Autoimmune Gastritis? 

The exact cause of autoimmune gastritis is not fully understood, but it’s likely the result of a combination of genetic, environmental, and immune-related triggers. Risk factors include a personal or family history of autoimmune disease, older age, and being of the female sex. People with other autoimmune conditions, such as Hashimoto’s thyroiditis, type 1 diabetes, or vitiligo, are at higher risk of AIG 5.

It’s worth noting that not everyone with these risk factors develops AIG. Individual variability means the exact combination of causes can differ from person to person.

How Autoimmune Gastritis Is Diagnosed

Early diagnosis of AIG is key to preventing longer-term complications, such as gastric cancer or severe nutrient deficiencies. Diagnosing AIG typically requires a combination of the tests listed below 5.  

Individuals who have other autoimmune diseases, unexplained iron-deficiency (with or without anemia), or B12 deficiency, and those with unexplained neuropsychiatric symptoms may warrant evaluation for autoimmune atrophic gastritis. Targeted assessment may also be considered in selected patients with fertility issues 4. 

Blood Tests for Autoimmune Gastritis

Blood tests for AIG may measure:

• Gastrin (a hormone that stimulates stomach acid production) 5
• Pepsinogen (an enzyme linked to stomach acid secretion) 5
• Parietal cell antibodies (considered the hallmark of AIG) 4
• H. pylori antibodies 5

Gastrin and pepsinogen levels can give clues about the health of your stomach lining.

Even though parietal cell antibody tests are popular in functional medicine, they aren’t reliable on their own. These antibodies can also appear in other autoimmune conditions, including autoimmune thyroid disease and celiac disease 8. 

Additionally, parietal cell antibodies may only be elevated in the early stages of autoimmune gastritis, sometimes decreasing as the disease progresses. This can make results confusing or misleading 5 9.

Endoscopy and Biopsy

Gastric endoscopy involves inserting a thin tube with a camera into the stomach to examine the lining. This endoscopic surveillance can detect early-stage cell abnormalities. 

But to properly confirm an AIG diagnosis, your doctor may order a biopsy of the fundus (top part of the stomach) and possibly of the antrum (bottom part of the stomach)—also known as an antral biopsy.

Although it’s more invasive than a blood test, the gastric endoscopy is the gold standard for diagnosing AIG 4. 

Autoimmune Gastritis, Gut Health, and Leaky Gut

When it comes to autoimmune gastritis, long-term improvement means looking at what’s driving the immune system in the first place. For many people, that includes taking a closer look at gut health.

Why the gut? Across a wide range of autoimmune conditions, we consistently see shifts in the gut microbiome—meaning the community of bacteria in the gut isn’t as balanced or resilient as it should be. These imbalances can fuel inflammation and may contribute to issues like increased intestinal permeability (“leaky gut”), which can keep the immune system on high alert 10.

Supporting gut health is often a practical starting point for calming the immune response and creating better conditions for healing.

In particular, studies have linked autoimmune diseases with increased intestinal permeability, or leaky gut 11. A leaky gut can allow foreign substances to enter the bloodstream and trigger the immune system to go into overdrive.

A study of 266 volunteers found that those with increased intestinal permeability had higher levels of self-attacking antibodies than those with a healthy gut lining. Self-attacking antibodies related to intestinal tight junctions were strongly linked to those found in autoimmune diseases, including AIG 12. 

This and other evidence suggest that a leaky gut may contribute to the development of autoimmune conditions, including AIG, type-1 diabetes, multiple sclerosis, and Crohn’s disease. 

Whatever autoimmune disease may be present, improving the balance of gut bacteria to strengthen the intestinal lining may help keep autoimmunity at bay.

Treatment for Autoimmune Gastritis

At the clinic, we’ve found that autoimmune gastritis can be well managed with a holistic approach that combines dietary changes and targeted supplements. This combination can be very helpful for balancing gut bacteria, improving gut health, and supporting autoimmune conditions.

Gut-Friendly Diets for Autoimmune Gastritis

In our clinic, we start by removing the foods most likely to drive inflammation or disrupt the microbiome. This mainly includes ultra-processed foods (UPFs) such as sweets, refined breads, fast food, deli meats, and sugary drinks. Regularly eating these may increase inflammatory activity and autoimmune risk 13.

Our first nutritional step is usually a Paleo diet, focused on whole, unprocessed foods and minimal wheat and dairy. Although it hasn’t been studied specifically for autoimmune gastritis, it has shown benefits in autoimmune thyroid disease and is a solid starting point for calming an overactive immune system 14.

If symptoms don’t improve on Paleo, many of our clients respond well to a low-FODMAP diet, which reduces fermentable carbohydrates that can feed bacterial overgrowth. (Here’s our downloadable low-FODMAP guide.)

The Autoimmune Protocol (AIP) is a more restrictive Paleo variation. It has shown promise for inflammatory bowel disease and Hashimoto’s, but it hasn’t been studied in AIG 15 16. For that reason, we reserve it for cases that don’t improve with simpler approaches.

Across all diets, our rule is simple: Start with the least restrictive option and increase structure only when necessary. Overly strict diets followed for too long may lead to nutrient gaps that may worsen AIG symptoms.

Lifestyle habits help, too. Eating smaller, more frequent meals, avoiding personal trigger foods (such as caffeine, alcohol, or spicy foods), and using stress-reduction practices like gentle movement or breathwork may offer additional symptom relief.

Supplements for Autoimmune Gastritis

Once you’re supporting your body with a gut-healthy diet, you may be able to further minimize symptoms of AIG with targeted supplements. 

Vitamin B12

Autoimmune gastritis destroys cells that produce intrinsic factor, the protein we need for vitamin B12 absorption. As a result, those with AIG usually need high doses of vitamin B12 if a deficiency is present.

Studies on the effect of vitamin B12 in autoimmune gastritis have shown that:

• When implemented early in AIG, vitamin B12 combined with iron (see below) may prevent anemia and neurological problems that can develop from autoimmune gastritis 5.
• Compared to oral vitamin B12, injections may reduce anti-parietal cell antibodies by more than half and help to reduce stomach autoimmunity 17. 

Traditionally, vitamin B12 is injected directly into the muscle to get around absorption problems in AIG, but this might not always be necessary. For example, limited research has shown that high oral B12 doses can be as effective as injections in some people with AIG and those with B12 deficiency 18. 

Regardless, always discuss B12 supplementation with a doctor to find out what works best for you.

Iron

Reduced stomach acid in AIG makes dietary iron less absorbable, increasing the risk of iron deficiency anemia. 

Iron supplements are often required to prevent or correct iron deficiency in autoimmune gastritis 5. Finding out the best way to get iron (supplements or injections) and regularly monitoring iron levels is an important part of living with AIG.

Probiotics

Probiotics are an excellent way to repair a leaky gut and put a damper on autoimmunity. That’s why I strongly recommend that my clients with autoimmune gastritis start taking probiotics.

There’s not much research directly examining the benefits of probiotics for autoimmune gastritis. But plenty of studies show that probiotics can help with autoimmune diseases in general by improving gut health and reducing gut permeability 19 20.

Probiotics may also help if a coexisting H. pylori infection is contributing to AIG. A 2018 systematic review found that even when taken alone (without antibiotics), multi-strain probiotics eradicated H. pylori in 14% of cases (21). 

But as a meta-analysis (a high-quality study of studies) found, adding probiotics to conventional treatment has been shown to work best 22.

In the clinic, we usually get the best results when using multi-strain probiotics, specifically a blend of:

• Lactobacillus and Bifidobacterium species
• Soil-derived bacteria (Bacillus species)
• Saccharomyces boulardii (a beneficial yeast)

For convenience, we’ve formulated a 3-in-1 blend that combines these probiotics, is easy to use, and requires no refrigeration. 

Gut-Rebuilding Glutamine

Glutamine is an important part of the gut-rebuild supplement protocol we use in the clinic to help rebuild the gut lining 23. 

While not yet studied for its effects on autoimmune gastritis, glutamine can repair a leaky gut and improve symptoms in people with increased intestinal permeability and diarrhea-predominant irritable bowel syndrome (IBS-D) 24.

Betaine Hydrochloric Acid

Not only can AIG cause B12 and iron deficiencies, but the lack of stomach acid may also cause insufficient absorption of vitamin C, calcium, and vitamin D 25. 

And if you use proton pump inhibitors, be aware that they can further worsen iron and nutrient absorption 26.

Although it hasn’t been researched in people with AIG, betaine hydrochloric acid (HCl) can improve poor digestion related to low stomach acid and may be worth a try with a doctor’s supervision 25. 

Whether HCl helps or not, assessing nutrient levels periodically with clinical guidance is wise for anyone with AIG. A knowledgeable healthcare provider can help locate the right supplements to stay balanced.

Living Well With Autoimmune Gastritis

Though autoimmune gastritis symptoms can range from uncomfortable to debilitating, the right care can help you manage the condition and your symptoms. Supporting gut health and nutrient absorption with diet changes and supplements is key.

If you’re at higher risk—such as being over 60, having a family history of autoimmune conditions, or having a history of H. pylori infection—early screening and intervention may help reduce the risk of long-term complications. While current treatments primarily focus on managing symptoms and nutrient deficiencies, emerging research is exploring ways to halt gastric atrophy, support mucosal healing, and potentially lower cancer risk. However, these approaches remain experimental, and clinical guidelines continue to emphasize surveillance and individualized care.

It’s also important to talk to a healthcare professional to ensure you have the right diagnosis and treatment plan for your own needs. If you need help with this, you can reach out to us at the Ruscio Institute for Functional Health for a consultation.

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