Longevity entrepreneur Bryan Johnson has been diagnosed with autoimmune gastritis, a chronic inflammatory condition in which antibodies destroy acid-producing cells in the stomach. Johnson announced his intent to address the condition, writing on X, "I have an autoimmune disease. My stomach is eating itself." He added, "I'm going to try and solve it."

Autoimmune gastritis prevents people from absorbing iron and is linked to deficiencies in vitamin B12, which can cause anemia and neurological complications. The condition is also linked to an increased risk of stomach cancer. Johnson, who is 48 years old, received a 1,000 mg Monoferric iron infusion following his diagnosis. His blood results showed elevated levels of anti-parietal-cells-antibodies, and stomach biopsies showed early weakening of the stomach lining.

Mimi Chang Tan, an assistant professor of gastroenterology at Baylor College of Medicine, said the specific cause of autoimmune gastritis is not known but may involve genetic factors, environmental triggers, and chronic inflammation. She said autoimmune gastritis "is notoriously insidious and frequently remains silent for decades, with symptoms often presenting outside of the gastrointestinal tract as fatigue, weakness, or neurological issues." Chang Tan said, "Anyone with low ferritin levels or iron deficiency anemia warrants an upper endoscopy and colonoscopy to screen not only for AIG but other causes of anemia." Patients with autoimmune gastritis are 13 times more likely to develop neuroendocrine tumors.

Johnson wrote on X, "Guys, I'm an idiot," and added, "All this time I've spent trying not to die, I had toxic turf." Toby Cornish, a gastrointestinal pathologist and professor at the Medical College of Wisconsin, characterized Johnson's suggestion of a link between his childhood diet and autoimmune gastritis as "highly speculative." Cornish said, "I think gastroenterologists should really be sampling more 'normal'-appearing stomachs in patients with a history of iron deficiency that's been treated," because "many of those patients will actually turn out to have autoimmune gastritis."

Why It Matters

Autoimmune gastritis affects an estimated 4% of people worldwide. The U.S. Preventive Services Task Force recommends people start getting colonoscopies at age 45; guidelines for starting colonoscopies were lowered from age 50 to age 45 in 2021. Johnson was diagnosed with hypothyroidism at age 21.