Biohacker Bryan Johnson reveals autoimmune gastritis diagnosis, pushes back against critics

Diagnosis after years of mystery

Bryan Johnson, the 48-year-old tech entrepreneur who sold Braintree to PayPal for $800 million and later founded Kernel, has built a public persona around his $2 million-a-year Project Blueprint to reverse biological aging. The subject of the 2025 Netflix documentary "Don't Die: The Man Who Wants to Live Forever" revealed on June 30 that he has autoimmune gastritis, a chronic condition in which the immune system attacks the stomach lining. The disease, also known as Biermer's disease, impairs absorption of iron and vitamin B12, causes persistent inflammation, and raises the long-term risk of stomach cancer. Johnson said the diagnosis was confirmed in May 2026, but for 11 years prior, his ferritin levels had been inexplicably low. "My stomach is eating itself," he wrote on X. Despite his exhaustive monitoring, the condition stayed hidden because other blood markers remained normal while the body depleted its iron reserves.

1. 2015Unexplained low ferritin levels persist for 11 years despite dietary and supplement interventions.
2. Early 2026Antibody levels found to be five times normal, prompting stomach tissue biopsy.
3. May 2026Diagnosis of autoimmune gastritis confirmed.
4. Jun 30, 2026Johnson publicly announces the diagnosis on X.

Johnson's response to critics

The announcement prompted online criticism suggesting that his extreme anti-aging regimen, which includes hyperbaric oxygen therapy, plasma transfusions from his teenage son, and a strict 1,977-calorie vegan diet, might have triggered the disease. Johnson rejected those claims in a series of lengthy posts, arguing that his openness about health data exposes others' denial.

The anesthesia only works if everyone does it together. One abstainer reveals to the room that they are drunk.

He attributed the condition to his earlier lifestyle of fast food, sugary drinks, and weight gain during his years as a young father and startup founder, a period that also included a severe depression. He also contended that many critics likely have undiagnosed health problems, mistaking the absence of a diagnosis for good health.

The limits of self-measurement

Johnson's case has drawn particular attention in Berlin, which has emerged as a European center for the longevity and self-quantification movement. The city is home to clinics like Years, which offers full-day diagnostic assessments, and recently hosted the Life Summit with over 3,000 attendees and 120 speakers. The industry's core promise is that comprehensive measurement leads to early detection. Johnson, who describes himself as the most biologically measured person in history, now serves as an unintentional counterexample: even with his resources and constant data collection, the disease progressed silently for more than a decade.

What's next

Autoimmune gastritis has no cure, but Johnson intends to pursue an unconventional path. He plans to use single-cell sequencing to analyze one million immune cells from his stomach, identifying the specific lymphocyte receptors responsible for the attack.

I'm going to try and solve it. Will share all.

Standard treatment involves vitamin B12 injections and regular endoscopic monitoring, but Johnson's team aims to intervene at the immunological level. In a reflective note, he urged his followers to prioritize health, writing that people fill their days with trivialities until health becomes the only thing that matters.