[19] In 2022, he received an honorary doctoral degree from the University of Bordeaux (Docteur honoris causa)[20] Blaser is best known[21] for his studies of Helicobacter pylori and its relationship with human diseases.
[22][23] Initially dismissive and skeptical of Nobel laureate Barry Marshall's findings of H. pylori's relationship to gastric and peptic ulcers, which Blaser described as "the most preposterous thing I’d ever heard; I thought, this guy is a madman,”[24][25] Blaser's work nonetheless later helped establish the role of H. pylori in the causation of gastric cancer, the second leading cause of cancer death in the world.
[31] Despite considerable and ongoing skepticism by the community of H. pylori investigators, Blaser and his colleagues progressively developed a body of research that provided evidence that gastric colonization by this organism provided protection against the esophageal diseases of gastroesophageal reflux disease (GERD), Barrett's esophagus, and esophageal adenocarcinoma, work that has since been confirmed by independent investigators.
Since then, acagia has come to reflect the rise in other diseases associated with the loss of cagA+ H. pylori, and may become a metaphor for the disappearance of members of the human microbiome that have symbiotic roles.
[34] He envisioned a step-wise (generational) diminution in microbial diversity, especially in early life to explain the epidemic rise of such diseases as childhood-onset asthma and obesity.
[35] He has proposed that the routine use (and overuse) of antibiotics in young children may be causing collateral damage, with extinctions of our ancient microbiota at critical stages of early life.
[36] Studies in mice have contributed strong support to these hypotheses.,[37][38][39] and on-going work in children with reference to many diseases,[40] including asthma,[41][42][43] show the importance of early life microbiome perturbation in increasing risk.
[44] Recent studies with colleagues at the Mayo Clinic have shown a strong association of antibiotic exposure before the age of two and the development of multiple condition in later childhood, including asthma, eczema, overweight and obesity, ADHD, and learning disability,[45] providing further support for his hypothesis.
His studies in mice provide evidence that the effects of antibiotic perturbation on the microbiota can be transmitted via the mother to the next generation, affecting both intestinal micro-ecology and disease manifestations.
Professional science writer Sandra Blakeslee helped write Missing Microbes[49], which was published by Henry Holt and Co. in April 2014, and has been translated into 20 languages.
Under the leadership of his wife, Dr. Maria Gloria Dominguez Bello, a group of scientists have formed the Microbiota Vault, Inc. (www.microbiotavault.org ), a not-for-profit non-governmental organization (NGO) public charity in the United States; Blaser serves as a member of the Board of Directors and an officer of the Foundation.