Entrepreneur Bryan Johnson recently announced that he has been diagnosed with autoimmune gastritis (AIG), a chronic autoimmune disease in which the immune system mistakenly attacks the stomach’s acid-producing parietal cells. Johnson shared that years of unexplained low iron stores eventually led to additional testing, including blood work, endoscopy, and stomach biopsies, which confirmed his diagnosis.
Even with exceptional access to healthcare and continuous health monitoring, autoimmune gastritis can remain hidden for years.
Persistent iron deficiency may be one of the earliest warning signs of autoimmune gastritis, but the disease often goes unrecognized because early symptoms can be vague or absent altogether. Diagnosis typically relies on a combination of clinical evaluation, laboratory testing, endoscopy, and stomach biopsies rather than any single definitive test.
Johnson’s diagnosis has also sparked discussion about whether his vegan diet or other lifestyle factors played a role in the development of autoimmune gastritis. While the exact cause of autoimmune gastritis remains unknown, current research suggests the disease develops through a complex interaction of genetic susceptibility, immune system dysfunction, and environmental factors.
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Research has made significant progress in understanding the factors that drive autoimmune gastritis.
Rather than being caused by a single malfunction of the immune system, studies now suggest that the disease develops through a complex interplay among immune cells, inflammatory signaling pathways, autoantibodies, and changes within the stomach itself. Scientists are also investigating how disruptions to the stomach microbiome and breakdowns in the immune system’s normal regulatory mechanisms may contribute to disease progression, helping to paint a more complete picture of how autoimmune gastritis develops.
Researchers have found that autoimmune gastritis frequently coexists with autoimmune thyroid disease, type 1 diabetes, vitiligo, and other autoimmune conditions, leading experts to increasingly view it as part of a broader autoimmune spectrum rather than simply a disorder of the stomach. This growing understanding may help identify people at higher risk and support earlier screening and diagnosis in individuals living with related autoimmune diseases.
Although there is currently no cure for autoimmune gastritis, research is advancing rapidly.
Scientists are developing improved diagnostic strategies that combine blood biomarkers, including anti-parietal cell antibodies, intrinsic factor antibodies, gastrin, and pepsinogen levels, with endoscopic and biopsy findings to help detect the disease earlier. More personalized approaches to predicting autoimmune gastritis progression and therapies that target the underlying autoimmune process rather than simply treating its complications are also being explored. Emerging areas of research include restoring immune tolerance, microbiome-based therapies, precision risk stratification, and targeted treatments such as netazepide, though these approaches remain investigational.
Johnson’s diagnosis is a reminder that autoimmune gastritis can remain hidden for years, even in people who actively monitor their health. As researchers continue to unravel the biology of the disease, these discoveries are laying the foundation for earlier diagnosis, more personalized care, and future therapies that address the underlying autoimmune process rather than only managing its long-term complications.
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Feng, M., Xu, W., & Zhu, H. (2026). Autoimmune gastritis: a comprehensive review of pathophysiology, risk stratification, and management. Frontiers in immunology, 17, 1878128. https://doi.org/10.3389/fimmu.2026.1878128
Soykan, İ., Er, R. E., Baykara, Y., & Kalkan, C. (2024). Unraveling the Mysteries of Autoimmune Gastritis. The Turkish journal of gastroenterology : the official journal of Turkish Society of Gastroenterology, 36(3), 135–144. https://doi.org/10.5152/tjg.2024.24563
