Billionaire Brian Johnson Diagnosed with Autoimmune Gastritis, Experts Explain Risks

Brian Johnson, known as "the healthiest man alive," revealed on July 6, 2026, that he has been diagnosed with autoimmune gastritis, a chronic condition where the immune system attacks the stomach lining. Johnson, 48, has invested millions in efforts to halt aging, but this diagnosis sheds light on previous health issues he has faced. Autoimmune gastritis affects only about 2% to 5% of the population and can cause the stomach to produce less acid and reduce absorption of vitamin B12, according to Professor Adi Lehat, head of the Gastroenterology Institute at Assuta Ashdod Hospital.

Lehat explained that the immune system mistakenly attacks healthy stomach tissue, primarily damaging specific stomach areas. The disease can progress silently for years, sometimes detected through blood tests showing iron deficiency or anemia. Symptoms, when present, include upper abdominal discomfort, bloating, nausea, and fatigue. Long-term vitamin B12 deficiency may lead to numbness in limbs, sensory loss, or balance problems. Johnson’s diagnosis aligns with his medical history, as he has had hypothyroidism since age 21, a condition often linked to autoimmune gastritis.

Stress and depression, which Johnson has reported experiencing, may exacerbate immune system dysfunction and trigger autoimmune diseases in predisposed individuals. The main implication of this diagnosis is the need for regular medical monitoring. Persistent inflammation and changes in the stomach lining can increase the risk of precancerous lesions or stomach cancer, though most patients with autoimmune gastritis do not develop malignancies. Monitoring typically involves gastroscopy and biopsies to detect early changes and manage the condition effectively.