American tech entrepreneur and longevity advocate Bryan Johnson has revealed he has been diagnosed with an incurable autoimmune disease.

The 48-year-old, who has become one of the world’s most recognisable biohackers through his multi-million-dollar anti-ageing experiment Project Blueprint, announced he has autoimmune gastritis (AIG), a rare disorder in which the body’s immune system attacks the stomach’s lining.

Mr Johnson shared the diagnosis in a lengthy post on X, writing: “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.”

”It’s called Autoimmune Gastritis (AIG). My hypothyroidism got diagnosed when I was 21 years old with a routine blood draw,” he added.

“That enabled me to begin proactive management, supplementing levothyroxine and Armour Thyroid. They are the hormones my body should be producing on its own but wasn’t.

“By taking these pills daily, my body was able to operate as though my thyroid was functioning properly.

“What I didn’t know was that something else was going on inside my body: my stomach had begun attacking itself. But there was no routine test to find out and I didn’t have any symptoms.”

Mr Johnson explained the condition went diagnosed for years, reflecting on his childhood regularly eating sugary foods.

“As a kid, I ate sugar cereal, drank sugary soda, and gobbled down fast food. I had a few healthy years in my early 20s but then became a young father of three and began building a business,” he said.

“Juggling that stress and grind, I let my health slip and gained 40 lbs. Within a few years I’d fallen into a deep, chronic depression. Somewhere in that timeline, my body began developing an autoimmune process affecting my thyroid and then my stomach lining.

“I just discovered it in May. I’m unsure how long I’ve had it. AIG causes irreversible damage: nutritional deficiency, anemia, and over a long horizon, elevated cancer risk.

“When AIG is discovered today, standard medical care concedes defeat, stating that nothing can be done except managing the condition, no matter how awful or lethal the effects.

“Looking back over the past few years, I can now see the early signals we were picking up in measurement but hadn’t connected the dots. For 11 years, I’ve had low ferritin, without anemia. We continually tried to raise my iron levels with food and supplementation but nothing would work.”

True to his reputation as an advocate for “conquering death”, the biohacker vowed to continue pursuing new treatments to manage the condition.

“My team and I are going to try and solve my AIG. This is how we’re approaching it: First, routine monitoring keeps the disease in view: ferritin and iron, B12, the pepsinogen I/II ratio, gastrin, and chromogranin A. Gastrin is the dial to watch.,” the post continued.

“If it climbs, the disease is advancing, and the risk of gastric neuroendocrine tumors climbs with it. Second, we’re doing advanced characterization of the disease.

“We’ll do a repeat biopsy to read the immune infiltrate, deep cytokine profiling, and T-cell subset analysis, to see which pathways are actually firing.

“That testing drives the intervention plan, including the experimental approaches we intend to develop.”

According to the Global Autoimmune Institute, autoimmune gastritis is a rare inflammatory condition where the body’s antibodies attack acid producing cells that make up the stomach lining.

Although autoimmune gastritis is often asymptomatic in its early stages, symptoms can include:

• Upper abdominal pain
• Heartburn
• Bloating
• Feeling full quickly
• Fatigue
• Shortness of breath
• Weakness
• Sensory changes
• Balance problems