Is Your Stomach Eating Itself? What To Know About This Autoimmune Condition
Bryan Johnson is an entrepreneur and venture capitalist, but what he is really known for is his obsession with biohacking and longevity. He has gone viral for trying to achieve immortality, posting all of the tests and protocols he follows to stay in peak form.
But on Monday, Johnson revealed that he may not be the picture of perfect health. After months of struggling with fatigue, Johnson shared that he was diagnosed with autoimmune gastritis, a condition that he describes as the stomach "eating itself." It's not the most talked-about autoimmune condition, but it's more common than most people realize, and it tends to go undiagnosed for years.
If you've been struggling with unexplained fatigue, persistent anemia, or a foggy feeling you can't shake, and your doctors keep coming up empty, you might have it too. Here's what autoimmune gastritis is, why it's so easy to miss, and what to do if you think it might be affecting you.
What is autoimmune gastritis
According to a 2020 review published in Nature Reviews Disease Primers1, autoimmune gastritis is an increasingly prevalent, organ-specific immune-mediated disorder. It's a slow, progressive condition, which is part of why it often takes years to detect.
Everyone's stomach lining contains specialized cells called parietal cells. The job of parietal cells is to produce stomach acid and a protein called intrinsic factor, which is your body needs to absorb vitamin B12. In autoimmune gastritis1, the immune system mistakenly identifies these cells as a threat and begins attacking them. Over time, the parietal cells are destroyed and replaced with scar-like tissue, which means the stomach gradually loses its ability to produce acid and intrinsic factor.
The most common form of gastritis is called environmental metaplastic atrophic gastritis and is caused by an infection of H. pylori bacteria, which inflames the stomach lining.
Autoimmune gastritis is a different beast entirely. It's not caused by an infection, and antibiotics won't help. Instead, it's driven by the immune system turning on itself, and it tends to be restricted to a specific part of the stomach called the body or corpus, rather than spreading throughout.
While H. pylori-related gastritis and autoimmune gastritis can sometimes overlap, they are fundamentally different conditions with different causes, different patterns, and different management strategies.
Symptoms: why it's so hard to spot
Many people with autoimmune gastritis have no symptoms at all, at least not in the early stages. That same found that patients are often asymptomatic, or they may experience vague digestive complaints like bloating, heartburn, or a general sense of discomfort that's easy to chalk up to stress or diet.
Some people with autoimmune gastritis are prescribed acid-reducing medications for their heartburn or reflux symptoms, but this may make symptoms worse because the stomach is already producing less acid than it should.
Because the symptoms are so nonspecific, autoimmune gastritis is frequently misdiagnosed or simply missed. Research notes that poor recognition of this condition2 often leads to inadequate management and delays in identifying who needs closer monitoring. The condition often only gets identified when a small tissue sample is taken from the stomach lining during an unrelated procedure, and a pathologist spots the characteristic changes in the tissue.
The downstream effects
The real consequences of autoimmune gastritis tend to show up not in the stomach itself, but throughout the rest of the body. When the stomach can no longer produce enough intrinsic factor, vitamin B12 absorption breaks down. When acid production drops, iron absorption suffers too. The result is a cascade of deficiencies that can affect energy, cognition, and the nervous system.
The most well-known downstream condition is pernicious anemia, a form of B12 deficiency anemia historically associated with autoimmune gastritis. But the effects can go further.
Research shows2 the condition can also lead to neurological symptoms, including numbness, tingling, memory issues, and mood changes, which can be traced back to long-standing B12 deficiency.
Iron deficiency is also common and often shows up before B12 deficiency does, which is why unexplained iron-deficiency anemia, especially in someone who doesn't have an obvious reason for it, can sometimes be an early clue of autoimmune gastritis.
There is also a long-term risk to be aware of. Research has found that autoimmune gastritis is associated with an increased risk of certain stomach tumors, including a neuroendocrine tumor and, less commonly, gastric cancer, with incidence rates of 2.8% and 0.5% per person per year2, respectively.
Who is most at risk
Autoimmune gastritis can affect anyone, but certain groups are more likely to develop it. It's more common in women, and it tends to be diagnosed in middle age and beyond, though it can appear earlier. The estimated prevalence2 is between 0.3% and 2.7% in the general population.
The condition also has a strong connection to other autoimmune diseases. People with autoimmune thyroid conditions, such as Hashimoto's disease, and those with type 1 diabetes are at higher risk. Clinical guidelines 3specifically recommend that providers screen for autoimmune thyroid disease in anyone diagnosed with autoimmune gastritis.
If you already have an autoimmune condition, it's worth asking your doctor whether screening makes sense, particularly if you're experiencing unexplained anemia or fatigue. Research has also explored the broader triggers behind autoimmune conditions and why some people are more susceptible than others.
How it's diagnosed
Diagnosing autoimmune gastritis typically involves a combination of blood tests and a stomach biopsy3.
On the blood work side, doctors look for anti-parietal cell antibodies, the immune proteins that signal the body is attacking its own stomach cells, as well as levels of B12 and iron.
The definitive diagnosis comes from examining a tissue sample gathered during an upper endoscopy. A pathologist examines the tissue and looks for the characteristic pattern of damage to the stomach lining.
Diagnostic delay is common. Because the symptoms are vague and the condition is often overlooked, many people live with autoimmune gastritis for years before getting a clear answer.
What you can do
There is currently no treatment that reverses the underlying immune process in autoimmune gastritis. But there is a lot that can be done to manage the condition and protect long-term health.
- B12 supplementation: Because oral B12 absorption is impaired when that essential stomach protein is lacking, many people with autoimmune gastritis need B12 delivered in a way that bypasses the stomach, either through injections or high-dose under-the-tongue supplements. If you're considered about a lack of B12, talk to your doctor about which form is right for you.
- Iron supplementation: Iron deficiency is common and should be monitored and treated. Your doctor can check your iron levels and recommend the appropriate form and dose.
- Endoscopic surveillance: Because of the elevated risk of stomach tumors, regular endoscopic monitoring is recommended. Guidelines advise that surveillance be considered based on individualized assessment and shared decision-making.
- Screening for related conditions: If you have autoimmune gastritis, your doctor should also screen for autoimmune thyroid disease and other related conditions, given the overlap.
- Rethink acid suppressants: If you've been prescribed acid-reducing medications for reflux or heartburn and you have autoimmune gastritis, bring this up with your doctor. Because the stomach is already low in acid, these medications may not be appropriate.
The takeaway
Autoimmune gastritis is a real, diagnosable condition that affects more people than most realize, and it's one that tends to hide in plain sight. Even people who seem perfectly healthy, like Bryan Johnson, can be struggling with it.
If you've been dealing with unexplained fatigue, persistent anemia, or neurological symptoms that don't have a clear cause, it's worth raising this condition with your doctor and asking about the relevant blood tests. Catching it early means you can get ahead of the deficiencies and protect your long-term health before more serious complications develop.
