Longevity entrepreneur Bryan Johnson diagnosed with autoimmune gastritis after a decade of monitoring

Bryan Johnson, founder of the Blueprint health program and the Immortals longevity initiative, disclosed in mid-2026 that he has autoimmune gastritis (AIG). The diagnosis was confirmed through elevated anti-parietal cell antibodies and a stomach biopsy showing early atrophy, despite a decade of intensive blood work and a 30-person medical team.

AIG is an autoimmune disorder in which the immune system attacks the stomach’s acid-producing parietal cells, impairing iron and vitamin B12 absorption. Johnson’s early indicator was consistently low ferritin levels for 11 years, which had not been fully explained. The condition can lead to iron-deficiency anemia, nerve damage and an increased risk of gastric cancer.

"My stomach is eating itself," Johnson wrote on Instagram.

Johnson, who has a history of autoimmune thyroid disease, said his lifestyle already aligns with standard gastritis recommendations, including avoiding smoking, alcohol and processed foods. He attributed possible contributing factors to earlier periods of high-sugar cereal consumption, fast food, and stress during his tenure as a CEO, though he noted this is speculative.

He is exploring experimental treatments such as JAK inhibitors, IL-17 blockers, CAR-T cell therapies and AI-designed antibodies, none of which are currently approved for AIG. Johnson emphasized that a condition should not be deemed incurable simply because existing therapies have not yet succeeded.

The case highlights challenges for the quantified-self movement, suggesting that even comprehensive self-tracking may miss slowly progressing diseases. Johnson has received intravenous iron infusions to address his deficiency, but the underlying autoimmune process remains untreated.