Bryan Johnson, the tech entrepreneur known for spending heavily on trying to slow his own aging, has told The Axios Show that he would not trust artificial intelligence with his health1. The comments come months after he said he had been diagnosed with an incurable autoimmune disease1. In a June post on X, he named it as autoimmune gastritis, a condition in which the immune system attacks the lining of the stomach2.
This is the first Biohack article following Johnson’s Blueprint regimen. It covers both his diagnosis and his latest public remarks, which are his own statements rather than the results of any study.
What Johnson said about AI and health
Johnson’s warning was aimed at the many people now asking chatbots about their symptoms1. On The Axios Show, he said:
We are in an in-between state where AIs are brilliant and dumb. They make really stupid mistakes all the time. I would never trust my health to an AI.
That quote was reported by The Economic Times1. Johnson did not reject the technology outright. He added that AI could eventually lead to major breakthroughs in medicine and longevity, and he said he hopes it will find a treatment or ways to slow or reverse aging1. He is also training AI agents on his brain and personality, aiming to keep some version of himself after death, while still hoping to keep living in his current body1.
The remarks land as chatbot use for health keeps growing. A Pew Research Center survey found that about one in four Americans say they have used AI chatbots to diagnose health symptoms1. More than one in five adults worldwide are reportedly asking chatbots such as ChatGPT and Gemini health questions directly1.
The diagnosis he disclosed in June
Johnson first described his condition in a long post on X on June 30, 20262. It began:
Bad news #1: I have an autoimmune disease. My stomach is eating itself. Bad news #2: 2–5% of people have this, too. Likely more, because it hides. Good news: I’m going to try and solve it. Will share all.
That text was reproduced by Business Standard2. The share of people affected is Johnson’s own figure; the sources here do not check it independently.
He said the diagnosis followed years of persistently low iron, even after he changed his diet and took supplements2. According to his account, routine tests did not find the cause at first, until specialised blood tests and stomach biopsies (small samples of tissue) confirmed the condition2. Medical Daily reported that the diagnosis surfaced after a routine colonoscopy at age 483. It also said Johnson had noticed his ferritin, a protein that reflects the body’s iron stores, was often low even though standard anemia markers were normal, which made the problem easy to dismiss3.
That detail matters to his story because Johnson is known for intense self-tracking. Medical Daily noted the disease was found despite years of what it called obsessive biological monitoring3.
What autoimmune gastritis is
According to the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), autoimmune gastritis happens when the immune system mistakenly attacks healthy cells in the stomach lining2. It is long-lasting and slowly damages the parietal cells, the cells that make stomach acid2. With less stomach acid, the body can absorb less iron, and over time this can lead to vitamin B12 deficiency2.
The disease itself may cause no symptoms2. When symptoms do appear, NIDDK says they usually come from complications such as low B12, low iron or anemia, and can include tiredness, weakness, dizziness, pale skin, tingling in the hands and feet, balance problems and trouble thinking2. Because some people feel nothing, it can go unnoticed until deficiencies or stomach damage turn up during a medical check2.
There is no cure. NIDDK says treatment focuses on managing complications rather than reversing the disease, and may include vitamin B12, iron or folic acid supplements depending on the person2. The US National Cancer Institute notes the condition is linked to a higher risk of stomach cancer, and some patients may need monitoring2.
What doctors said about his case
Some specialists said Johnson’s public disclosure could draw attention to a disease that is hard to catch3. Toby Cornish, a gastrointestinal pathologist at the Medical College of Wisconsin, told Medical Daily that the condition is often overlooked3:
Gastroenterologists should really be sampling more ‘normal’-appearing stomachs in patients with a history of iron deficiency that’s been treated, because many of those patients will actually turn out to have autoimmune gastritis.
Mimi Chang Tan, an assistant professor of gastroenterology at Baylor College of Medicine, described the disease to the same outlet as notoriously insidious3.
What this does and does not show
Everything in this story rests on Johnson’s own account and on general information about the disease. None of the sources describe his test results in detail, his treatment, or how far the condition has progressed. His comments on AI are an opinion, not a measurement of how accurate chatbots are.
Medical bodies have raised similar concerns about AI in health. Mayo Clinic says diagnosing and treating illness is too complex to leave entirely to a machine1. It notes that AI tools may not see a person’s full medical history, cannot examine a patient or run tests, and may not explain how they reached a conclusion1. It also warns that AI can give answers that sound convincing but are wrong, often called “hallucinations”1. In one example the clinic cited, two people described similar symptoms in different words, and the AI told only one of them to seek emergency care1. Mayo Clinic recommends using AI for general health education rather than diagnosis, and checking answers against reliable medical sources1.
Who Johnson is
Johnson founded the online payments company Braintree, which bought Venmo before PayPal acquired Braintree in 20132. He later founded Kernel, a company building brain-monitoring devices2. He is now best known for Project Blueprint, a strict regimen of diet, exercise, sleep, testing and constant tracking of body measurements, which he says is designed to lower his biological age2. He also founded Don’t Die, which Medical Daily described as a longevity brand he calls a religion3.
His Netflix documentary shows him taking more than 50 pills a day and trying experimental steps such as gene therapy, plasma transfusions and fat transfers2. One widely discussed experiment was a plasma exchange involving his teenage son and his father; Johnson later said it did not bring the benefits he had hoped for and stopped it2.
What to watch next
Johnson said in June that he plans to try to solve his condition and would “share all”2. Given that NIDDK describes treatment as managing complications rather than reversing the disease2, any claim he makes about improving it will be worth reading closely: what was measured, how, and whether anyone outside his team has checked it. His AI agent project, and whether he uses AI tools in his own health decisions despite his warning, are other threads to follow1.
