Bryan Johnson’s chronic disease is notoriously difficult to diagnose

Health Bryan Johnson’s chronic disease is notoriously difficult to diagnose Longevity entrepreneur Bryan Johnson is drawing attention to autoimmune gastritis. Manage alerts for this article Email this article Share this article By Sarah ToddJuly 8, 2026 Reporter, Commercial Determinants of Health Sarah Todd[email protected]Sarah covers how industries like food and tobacco affect Americans’ bodies and minds. Her interests include ultra-processed foods; smoke-free tobacco; and wellness trends like perimenopause products and peptides. Confidential tips can be sent on Signal at sarahlizchar.47. Longevity entrepreneur Bryan Johnson shared some bad news on social media recently. “I have an autoimmune disease. My stomach is eating itself,” he wrote on X. The good news? “I’m going to try and solve it.” The disease in question is autoimmune gastritis, a chronic inflammatory condition in which antibodies destroy acid-producing cells in the stomach, which prevents people from absorbing iron. It’s not in itself a fatal disease, but it is linked to an increased risk of stomach cancer and, eventually, to deficiencies in vitamin B12, which in turn causes anemia and neurological complications. Advertisement Autoimmune gastritis affects an estimated 4% of people worldwide, but it may be more common than we know: Experts say the disease is notoriously difficult to diagnose, and that gastroenterologists often fail to recognize it in patients. Now it’s in the spotlight thanks to Johnson, an unexpected spokesperson for any kind of disease, given the extreme measures he takes to protect and maintain his health. A 48-year-old multimillionaire biohacker whose Blueprint startup sells supplements, red-light laser therapy baseball caps to reverse hair loss, and other longevity-related wares, he’s also the founder of what he describes as a religion called Don’t Die. In recent years Johnson has accumulated millions of social-media followers and grabbed national headlines with his longevity efforts, at one point getting blood plasma transfusions from his teenage son.Johnson’s announcement is a reminder that no matter how much anyone strives to optimize his or her health, “you really can’t biohack your way completely out of disease or death,” said Jennifer Dowd, a professor of demography and population health at the University of Oxford. It may also be an opportunity to raise awareness about the importance of performing biopsies to diagnose an often-overlooked and hard to treat chronic disease, said Toby Cornish, a gastrointestinal pathologist and professor at the Medical College of Wisconsin. “I think gastroenterologists should really be sampling more ‘normal’-appearing stomachs in patients with a history of iron deficiency that’s been treated,” Cornish said, “because many of those patients will actually turn out to have autoimmune gastritis.”Advertisement What causes autoimmune gastritis? Johnson’s post explaining autoimmune gastritis is a pretty good explanation of the disease, according to Cornish. He and other experts do say there’s no specific research to support Johnson’s suggestion that there may be a link between his childhood diet of fast food, sugary cereals, and sodas, and later a 40-pound weight gain, and the condition.“I would call that highly speculative,” Cornish said. The specific cause of autoimmune gastritis isn’t known, but may be some combination of genetic factors, environmental triggers, and chronic inflammation, Mimi Chang Tan, an assistant professor of gastroenterology at Baylor College of Medicine, said via email. It is true that people with autoimmune thyroid disease, like Johnson, are more likely to be diagnosed with autoimmune gastritis, though one doesn’t cause the other. How is autoimmune gastritis diagnosed? For Johnson, the earliest symptom was his consistently low levels of ferritin — a blood protein that’s measured to show how the body is storing iron. But blood tests showed that his levels of hemoglobin and hematocrit, which are used to diagnose anemia, were fine. So the problem was easy to dismiss.Autoimmune gastritis “is notoriously insidious and frequently remains silent for decades, with symptoms often presenting outside of the gastrointestinal tract as fatigue, weakness, or neurological issues,” said Tan. Ferritin levels like Johnson’s are often an early sign, but a definitive diagnosis requires an upper endoscopy with biopsies. “Anyone with low ferritin levels or iron deficiency anemia warrants an upper endoscopy and colonoscopy to screen not only for AIG but other causes of anemia,” such as colorectal cancer, colon polyps, and a Helicobacter pylori stomach infection, said Tan. She notes that the latter three conditions are all more common than autoimmune gastritis. One noteworthy tidbit from Johnson’s post is the context he provides around the colonoscopy he received while searching for answers: “I was 48 years old and overdue.” The U.S. Preventive Services Task Force recommends people start getting colonoscopies at age 45. Why would Johnson — who’s called himself “the most biologically measured person ever” and spent $2 million on medical treatments in 2023 alone — be late for a routine screening?Advertisement Johnson didn’t respond to a request for comment. But Cornish notes that it was only recently, back in 2021, that guidelines lowered the age for starting colonoscopies from 50 to 45. “Sometimes people would get lost in the shuffle,” he said, particularly those in Johnson’s age group. And Johnson himself has admitted to having blind spots in the past. “Guys, I’m an idiot,” he wrote on X this spring. “All this time I’ve spent trying not to die, I had toxic turf” — that is, artificial grass, which some people worry exposes them to hazardous chemicals — in my backyard.” Treating autoimmune gastritis Johnson paints a bleak picture of treatment options for autoimmune gastritis: “standard medical care concedes defeat, stating that nothing can be done except managing the condition, no matter how awful or lethal the effects,” he writes. Unfortunately, Cornish said, it’s true that “we don’t really have good treatments for it.” People take iron orally or intravenously to address nutritional deficiencies, as Johnson did, and get monitored for stomach cancers. Patients with the condition are 13 times more likely to develop neuroendocrine tumors; the goal is to catch the tumors early enough that they can be treated endoscopically, rather than surgically. Patients with autoimmune gastritis also have a higher risk of adenocarcinomas, a serious form of cancer. The reason neuroendocrine tumors are so common in patients with the condition, said Cornish, is a “physiological feedback loop. When you have low acid in your stomach, the stomach tries to increase the acid levels by secreting gastrin, which is supposed to be increasing the acid levels. But when you no longer have parietal cells to make acid, the acid levels never come up and the stomach just makes more gastrin.” Enough gastrin eventually forms neuroendocrine tumors. If caught early, the prognosis tends to be good. Not content with these measures, Johnson said in his post that his team is looking at experimental interventions, including CAR-T therapy — a personalized form of gene therapy that’s proved promising in various autoimmune patients. Advertisement CAR-T therapy has not been well-studied for this particular condition, said Cornish. “It’s probably the best line of investigation for finding a cure in autoimmune gastritis. However, it’s still very early.” Still, he said, “it’s encouraging to know that people are exploring CAR-T for this because honestly, there’s not a lot you can do to help these patients.” For Johnson, the diagnosis comes as a relief. “You want to know if there is a problem with your body,” he wrote on X Tuesday. “Ignoring it doesn’t make it better. Delay just makes it harder, costlier, and riskier.” STAT’s coverage of chronic health issues is supported by a grant from Bloomberg Philanthropies. Our financial supporters are not involved in any decisions about our journalism. Cancer, chronic disease, Gene therapy, patients Submit a correction requestReprints Sarah Todd Reporter, Commercial Determinants of Health Sarah covers how industries like food and tobacco affect Americans’ bodies and minds. Her interests include ultra-processed foods; smoke-free tobacco; and wellness trends like perimenopause products and peptides. Confidential tips can be sent on Signal at sarahlizchar.47. 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