Bryan Johnson Diagnosed With Rare Autoimmune Disease, Says ‘Stomach Is Eating Itself’

Longevity entrepreneur Bryan Johnson has revealed he has autoimmune gastritis. Here's what the chronic autoimmune condition is and why his diagnosis is drawing attention.

Longevity entrepreneur Bryan Johnson has revealed he has been diagnosed with autoimmune gastritis.

Source : Instagram

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Key points generated by AI, verified by newsroom

• His case highlights hidden diseases despite close health monitoring.

Longevity entrepreneur Bryan Johnson has built a massive social media following by documenting his relentless pursuit of slowing the ageing process. Through his Blueprint program, he follows a rigorously controlled lifestyle that includes daily exercise, advanced medical imaging, frequent blood tests, a carefully managed diet, and experimental longevity therapies.

 ‘Stomach Is Eating Itself’

Johnson has also drawn global attention for his unconventional anti-ageing experiments, including a widely publicised plasma exchange involving himself, his teenage son, and his father. He later discontinued the procedure after saying it produced no measurable health benefits.

In a recent post on X, formerly Twitter, Johnson revealed that he has been diagnosed with autoimmune gastritis (AIG) despite nearly a decade of meticulous health monitoring. “My stomach is eating itself,” he wrote.

He explained that the diagnosis came after almost 10 years of persistently low ferritin levels - a marker of the body’s iron stores - that failed to improve despite dietary changes and oral iron supplements. Further investigations, including specialised blood tests and stomach biopsies, eventually confirmed autoimmune gastritis.

Bad news #1:

I have an autoimmune disease. My stomach is eating itself.

Bad news #2:

2–5% of people have this, too. Likely more, because it hides.

Good news:

I'm going to try and solve it. Will share all.

As a kid, I ate sugar cereal, drank sugary soda, and gobbled down… pic.twitter.com/EbJ8a916uS

— Bryan Johnson (@bryan_johnson) June 30, 2026

What Is Autoimmune Gastritis?

When the immune system unintentionally targets the parietal cells in the stomach that produce acid, it results in autoimmune gastritis. As a result, the stomach lining becomes damaged over time, and less stomach acid and intrinsic factor, a protein required for vitamin B12 absorption, are produced.

The National Health Service (NHS) states that if the disease is not properly monitored, it may eventually result in iron deficiency, vitamin B12 deficiency, pernicious anaemia, and an increased risk of some stomach malignancies.

Many patients have minimal symptoms in the early stages of the condition since it frequently develops gradually. Vitamin B12 deficiency, persistent weariness and unexplained low iron levels are some of the initial indicators that call for additional research.

Johnson explained that the illness had probably been advancing for years without any overt stomach symptoms. Rather, the initial indication was consistently low iron stores that did not improve with treatment. He claimed that previous medical assessments failed to determine the underlying cause because his hemoglobin stayed within the normal range. Johnson also disclosed that, at the age of 21, he received a diagnosis of hypothyroidism, another autoimmune disease. In retrospect, he thinks that autoimmune gastritis might have coexisted with it for a long time before it was eventually identified.

Johnson Sees The Diagnosis As His Next Scientific Challenge

Johnson says he is approaching autoimmune gastritis with the same data-driven mindset that has defined his longevity mission. He admitted that "there is no approved cure for autoimmune gastritis today" in his X post.

"Medicine treats it as something to manage, not solve," he continued, adding that he has no plans to end it.

"I'm going to try to solve it," he declared. He added that he intends to investigate new treatments targeted at reestablishing immunological tolerance while undergoing routine stomach biopsies, sophisticated immune profiling, and ongoing monitoring of alterations in his stomach lining. Johnson also voiced hope that autoimmune disorders that are currently thought to be incurable could ultimately be cured thanks to developments in biotechnology, protein engineering, artificial intelligence, and precision medicine.

"The lack of symptoms is not the presence of health," he said, reflecting on the larger lesson from his diagnosis and advising people to prioritise routine screening and preventive treatment.

Bryan Johnson's diagnosis highlights the complexity of autoimmune disorders and the importance of investigating persistent abnormalities such as unexplained iron deficiency rather than dismissing them as minor findings. Medical professionals stress that autoimmune gastritis is still rare but frequently goes unnoticed. Reducing problems and improving long-term results can be achieved through early diagnosis, routine follow-up and proper treatment of nutritional deficiencies.

Disclaimer: The information provided in the article is shared by experts and is intended for general informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition.