Bryan Johnson, the millionaire known for his anti-ageing pursuits, has revealed a battle with autoimmune gastritis, a condition where his immune system attacks his stomach. Despite his rigorous wellness regimen, the 48-year-old's decade-long struggle with low iron levels was finally diagnosed as this rare, often silent illness. Now, Johnson is assembling a research team to find a cure, emphasizing that feeling well doesn't guarantee good health and urging regular check-ups.