Bryan Johnson, the technology entrepreneur known for spending millions of dollars annually on longevity research, announced on July 15 that he has been diagnosed with autoimmune gastritis, a chronic condition in which the immune system attacks the lining of the stomach. Johnson made the announcement on X, describing the disease in stark terms.
"My stomach is eating itself," he wrote.
According to a report by Healthline, Johnson said the discovery came after years of low ferritin, which is a measure of the body's stored iron, despite dietary changes and oral iron supplements. He said he did not have anemia or recognizable symptoms. The condition was found only after his medical team pursued blood testing, an upper endoscopy, and stomach biopsies.
Johnson also addressed the current state of treatment options. "When AIG is discovered today, standard medical care concedes defeat, stating that nothing can be done except managing the condition, no matter how awful or lethal the effects," he wrote in the same post.
Experts say the condition is easy to miss. Felice Schnoll-Sussman, MD, a gastroenterologist at Weill Cornell Medicine and New York-Presbyterian, explained the challenge. "It can absolutely be missed, even in someone who is getting very thorough medical care. Autoimmune gastritis is often quiet for a long time, and when symptoms do occur, they can be very nonspecific things like fatigue, poor concentration, reduced stamina, indigestion, or just not feeling quite right," she said.
The condition affects an estimated 0.5% to 2% of people in the United States. It differs from the more common H. pylori gastritis, which is caused by a bacterial infection. Johnson said testing had already ruled out H. pylori, which helped his medical team pursue a different diagnosis.
Autoimmune gastritis targets parietal cells in the upper stomach. Those cells secrete hydrochloric acid, which helps break down food. When the immune system destroys them over time, the stomach loses its ability to absorb iron and vitamin B12 properly. By the time more obvious symptoms appear, some of the damage to the stomach lining may already be permanent.
There is currently no approved cure for the condition. Treatment focuses on identifying nutrient deficiencies, replacing iron and B12, and monitoring patients for potential complications. Johnson has said he intends to investigate experimental approaches, though experts emphasized that no such treatments are currently approved.
