Longevity ‘guru’ Bryan Johnson Reveals Autoimmune Gastritis Diagnosis: Early Signs, Symptoms

• Longevity “guru” Bryan Johnson has announced he has autoimmune gastritis, an incurable chronic condition of the stomach.
• Persistent iron deficiency may provide an early clue, even when anemia or other symptoms are absent. 
• There is no cure for autoimmune gastritis. Instead, treatment is focused on symptom management and monitoring.

Longevity “guru” Bryan Johnson announced he has been diagnosed with autoimmune gastritis, a chronic condition in which the immune system attacks the lining of the stomach.

Johnson announced the diagnosis on X, along with his intention to help “solve” the incurable condition.

“My stomach is eating itself,” he wrote.

 “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,” the post continues.

Johnson said that the discovery came after years of low ferritin — a measure of the body’s stored iron — despite dietary changes and oral iron supplements. He said he did not have anemia or recognizable symptoms, and the condition was discovered only after his medical team pursued blood testing, an upper endoscopy, and stomach biopsies.

The diagnosis highlights one of the central challenges of autoimmune gastritis: The condition can quietly damage the stomach for years before it causes anemia or other more obvious symptoms. By that point, a person may have difficulty absorbing iron or vitamin B12, and some of the damage to the stomach lining may be permanent.

“It can absolutely be missed, even in someone who is getting very thorough medical care. Autoimmune gastritis is often quiet for a long time, and when symptoms do occur, they can be very nonspecific things like fatigue, poor concentration, reduced stamina, indigestion, or just not feeling quite right,” said Felice Schnoll-Sussman, MD, Gastroenterologist at Weill Cornell Medicine and New York-Presbyterian 

Although Johnson has announced plans to investigate experimental approaches to the disease, experts emphasized that there is currently no approved cure. Treatment instead centers on identifying iron and B12 deficiency, replacing missing nutrients, and monitoring patients for potential complications.

What is autoimmune gastritis?

Gastritis is a broad term for inflammation of the stomach lining, but the underlying cause can differ from one patient to another.

In autoimmune gastritis, the body’s immune defenses mistakenly attack its own stomach tissue. Johnson described the disease as affecting parietal cells, which are found in the upper stomach and secrete hydrochloric acid to help break down food. 

This condition differs from H. pylori gastritis, which is far more common and driven by a bacterial infection. Johnson said testing had already established that he did not have H. pylori, helping his team hone in on a different diagnosis.

An estimated 0.5% to 2% of people in the United States may have autoimmune gastritis.

Autoimmune gastritis can interfere with the absorption of iron and vitamin B12. Some early signs include iron or B12 deficiency and, potentially, anemia related to one or both deficiencies.

The signs may be subtle. 

“The overwhelming majority of these cases are asymptomatic,” said Ashkan Farhadi, MD, board certified gastroenterologist at MemorialCare Orange Coast Medical Center in Fountain Valley, California.

Iron deficiency is associated with fatigue, weakness, and a pale complexion. B12 deficiency can have similar symptoms, as well as neurological ones, such as numbness and tingling in the hands or feet. 

Though autoimmune gastritis is hard to diagnose, persistent iron deficiency can be a clue.

“In patients with unexplained iron deficiency, whether or not anemia is already present, autoimmune atrophic gastritis should be considered as a possible cause, and an appropriate evaluation should be performed,” Schnoll-Sussman said.

Correcting an iron deficiency through supplementation does not stop the underlying autoimmune attack. The broader treatment strategy focuses on managing the results of stomach damage and watching for further changes.

“We are going after the consequences and preventing complications. Our role is damage control. We prevent the nutrients from becoming deficient. There is also a small chance of gastric cancer down the road. Because of that, interval endoscopy is sometimes recommended every 2 to 5 years,” Farhadi said.

Recent research estimates that gastric cancer develops in approximately 0.12% of patients with autoimmune gastritis each year, with a higher incidence among those with late-stage disease.

Johnson wants to “solve” autoimmune gastritis

There is currently no approved cure for autoimmune gastritis. Available care manages nutrient deficiencies and monitors for complications rather than modifying the immune response.

Johnson intends to pursue a more experimental program to “solve” the condition. He described plans to examine immune cells and inflammatory signals in his stomach, then use those findings to determine which immune pathways appear to be driving his disease.

However, he explicitly acknowledged the limits of his plans, noting there is “investigational preclinical evidence at best, and in several cases therapies that still have to be built.”

The timing of diagnosis could prove important if researchers eventually identify a way to interrupt the disease before extensive tissue loss occurs.

“There is growing interest in whether autoimmune gastritis could eventually be treated earlier in the disease process, before permanent damage to the stomach lining occurs. At the moment, however, that research is still preclinical,” Schnoll-Sussman said.

Farhadi cautioned against viewing the diagnosis only through the lens of damage inside the stomach.

“There is more to this condition than just the stomach. There are factors beyond it that aggravate things,” Farhadi said.

He pointed out that stress has increasingly been linked to problems in the gut, including the stomach and intestines.

Farhadi recommends supporting general health through a good diet, regular exercise, and stress management. These steps are not a cure for autoimmune gastritis, but they may form part of broader care while clinicians address deficiencies and monitor the disease.

Farhadi also takes a far more measured assessment of the condition than Johnson does, noting that it is rarely life threatening, and frequently asymptomatic to the point that individuals don’t even know they have it.

“This is how people make the news. If he had said I have a disease that is not that important and likely not going to affect my life, no one’s going to read that. From my perspective, we have a lot higher priorities when I see people in my clinic,” Farhadi said.