Bryan Johnson's Autoimmune Battle: 'Stomach Eating Itself'

American entrepreneur Bryan Johnson recently disclosed his diagnosis of autoimmune gastritis, a condition where his immune system mistakenly attacks his stomach. He revealed this autoimmune disease in a post on X, noting it affects an estimated 2-5% of the population, possibly more due to its often silent nature. Johnson expressed his intent to find a solution for the condition.

He detailed a history of diet and lifestyle factors contributing to his health, including a period of chronic depression and weight gain in his early thirties. His hypothyroidism was diagnosed at age 21. The autoimmune gastritis diagnosis, however, came in May 2026, a condition that can lead to nutritional deficiencies, anemia, and increased cancer risk over time. Johnson noted persistent low ferritin levels for 11 years, which standard treatments failed to rectify, pointing to an underlying issue with iron absorption.

Experts explain that autoimmune gastritis often develops subtly, with initial signs manifesting as fatigue or low iron levels rather than direct digestive symptoms. The condition impairs the stomach's ability to produce acid and intrinsic factor, crucial for vitamin B12 absorption. This can lead to anemia and other complications if left untreated. Autoimmune diseases, such as thyroid disorders, are known to co-occur with autoimmune gastritis, sometimes referred to as 'thyrogastric syndrome.'

Currently, there is no cure for autoimmune gastritis, with management focusing on addressing nutritional deficiencies and monitoring for complications. However, ongoing research in precision medicine offers hope for future treatments that could target the disease more effectively. Experts stress the importance of evaluating persistent fatigue or unexplained low iron levels, as these could signal underlying autoimmune processes.