"My Stomach Is Eating Itself": Bryan Johnson Diagnosed With Incurable Autoimmune Disease

Tech entrepreneur and longevity enthusiast Bryan Johnson has revealed that he has been diagnosed with autoimmune gastritis (AIG), a rare autoimmune disease in which the body's immune system mistakenly attacks the lining of the stomach. Johnson, 48, who is known for spending millions of dollars each year on therapies aimed at slowing ageing, shared the diagnosis in a detailed social media post, writing that his "stomach is eating itself". Although there is currently no cure for the condition, he said he intends to "try and solve it" using a combination of medical monitoring and experimental therapies.

According to Johnson, his health struggles began decades ago when he was diagnosed with hypothyroidism at the age of 21. While the condition was managed with hormone replacement therapy, he was unaware that another autoimmune disease was developing. He said the diagnosis of autoimmune gastritis was finally confirmed in May after years of persistently low ferritin (iron) levels that failed to improve despite dietary changes and iron supplements.

See the post here:

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

To identify the underlying cause, Johnson assembled a new medical team and underwent a series of tests, including a colonoscopy, upper endoscopy, specialised blood tests and stomach biopsies. While the colonoscopy was normal, blood tests detected elevated anti-parietal cell antibodies, and biopsies confirmed early-stage autoimmune gastritis.

Johnson said his iron deficiency has since been corrected with intravenous iron but acknowledged that there is no approved treatment that can reverse the disease. His team plans to closely monitor the condition while exploring investigational immune-based therapies. Among the approaches being studied are treatments aimed at stopping the immune cells attacking the stomach lining and AI-designed antibodies that could selectively target those cells. He stressed that these strategies remain experimental and are not part of standard medical care.

Reflecting on his younger years, Johnson said his lifestyle was far from the health-focused routine he follows today. He recalled growing up on fast food and sugary drinks before years of stress, weight gain and chronic depression preceded the onset of autoimmune disease.

Ending his post, Johnson urged people not to ignore persistent health issues, saying unexplained symptoms should be investigated rather than dismissed. "We fill our days mostly on things that are trivial next to what we ultimately care about. We know, deep down, however, that in the noise of it all, health is easily forgotten until it's the only thing that matters. We spend a fraction of our lives truly sober to the preciousness of life. We feel it when someone we love dies, when a child is born, when we come close to death ourselves, or when a diagnosis marks our limit. In those moments, we are sobered, and the rarity of it all becomes self evident. Imagine the existence we'd build together if that clarity didn't fade," he wrote.

What is Autoimmune Gastritis?

Autoimmune gastritis is a chronic condition in which the immune system mistakenly attacks healthy cells in the stomach lining, particularly the acid-producing parietal cells. Over time, this damages the stomach, reducing its ability to produce stomach acid and absorb essential nutrients such as iron and vitamin B12.

According to the Global Autoimmune Institute, the condition often develops gradually and can be difficult to diagnose because its early symptoms, including abdominal discomfort, bloating, heartburn, fatigue and iron deficiency, are non-specific and may resemble other digestive disorders. As a result, many cases are identified only after complications such as anaemia or vitamin B12 deficiency develop.

While there is currently no cure, treatment focuses on correcting nutritional deficiencies, monitoring disease progression and managing complications. Researchers are also investigating new immune-targeted therapies that could one day slow or stop the autoimmune process.