July 8, 2026, 8:29 am | Read time: 3 minutes
Few people monitor their bodies as meticulously as Bryan Johnson. The U.S. entrepreneur and longevity guru tracks his sleep, heart function, metabolic values, and even nighttime erections, takes numerous dietary supplements daily, and invests millions in his health. All the more surprising is his latest news: Johnson suffers from autoimmune gastritis—a chronic autoimmune disease that often goes unnoticed for years.
Longevity Guru Goes Public with Illness
On X (formerly Twitter), 48-year-old Bryan Johnson went public with his illness, describing it dramatically: “My stomach is eating itself.” He says he received the diagnosis in May 2026.
Low Iron Levels Were Apparently the First Warning Sign
There may have been signs of Johnson’s illness for years. The entrepreneur reports that his ferritin levels—a marker for the body’s iron stores—have been conspicuously low for about eleven years. However, no specific cause was found.
“What I wasn’t fully aware of until recently: how many opportunities my previous medical providers left unused. The low ferritin level was always downplayed but never addressed,” Johnson wrote.
In fact, unexplained iron deficiency is often considered one of the first signs of autoimmune gastritis. As stomach acid production decreases, iron from food is less well absorbed. Experts point out that those affected often do not develop any typical stomach complaints for many years, and the disease is therefore often recognized late.
Bryan Johnson Wants to Search for Answers
For Johnson, the diagnosis is particularly bitter. The tech millionaire has dedicated his life to the goal of slowing down the aging process as much as possible. His “Blueprint” program made him known worldwide, and Netflix even dedicated a documentary to him titled “Don’t Die–The Man Who Wants to Be Immortal.”
However, Johnson does not want to give up. In his post, he announced: “I’m going to try and solve it.” Together with his team, he wants to search for new scientific approaches.
What Exactly Is Autoimmune Gastritis?
Autoimmune gastritis (also called Type A gastritis) is a chronic inflammation of the stomach lining. In this condition, the immune system mistakenly attacks the so-called parietal cells of the stomach and the intrinsic factor. Both are crucial for the production of stomach acid and the absorption of vitamin B12.
The result: Nutrients like iron and vitamin B12 can no longer be adequately absorbed. In the long term, there is a risk of iron deficiency, anemia (pernicious anemia), and neurological complaints. Additionally, the disease is considered a risk factor for stomach cancer and certain neuroendocrine tumors.
Symptoms of Vitamin B12 Deficiency and How to Address Them
Effects, Dosage and Potential Risks of Vitamin B12 Supplementation
Why the Disease Often Remains Hidden for a Long Time
One of the most insidious aspects of autoimmune gastritis: Many patients do not notice the disease for a long time. Only when pronounced deficiencies develop do symptoms appear, including:
- persistent fatigue and exhaustion
- concentration problems and “brain fog”
- paleness and weakness
- heart palpitations
- tingling or numbness in hands and feet
- unsteady gait
- dizziness and neurological complaints
Often, the diagnosis is only made through blood tests and a gastroscopy with tissue samples.
No Cure–But Treatment Is Possible
According to current knowledge, autoimmune gastritis cannot be cured. Treatment primarily aims to control the consequences of the disease. These include:
- regular vitamin B12 supplementation, often by injection
- iron supplements if a deficiency is proven
- gastroenterological check-ups and gastroscopies to detect possible complications early
However, Johnson’s case also highlights an important insight of modern preventive medicine: Even extensive health monitoring cannot prevent every disease. Some illnesses develop almost unnoticed over many years—even in people who monitor their bodies more closely than almost anyone else.