The human stomach has its own microbiota, but it receives less scientific attention than the intestines — perhaps because acidic conditions, peristalsis, and the gastric mucus layer interfere with bacterial colonization. Nevertheless, characterizing the healthy gastric microbiota may be important for helping assess the future risk of gastric disease.

In this systematic review, the authors say researchers have detected five major phyla in the healthy human stomach: Firmicutes, Bacteroidites, Actinobacteria, Fusobacteria and Proteobacteria. The dominant genera are Prevotella, Streptococcus, Veillonella, Rothia and Haemophilus. As in the rest of the digestive tract, there is evidence that gastric microbiota composition can be affected by factors such as diet, drugs, and certain diseases.

For decades, scientists have debated how to interpret data on the relationship between Helicobacter pylori and gastric disease. This review discusses evidence that an individual’s pre-existing gastric microbiota may interact with H. pylori to contribute to the risk of gastric cancer and other diseases. Maintaining bacterial homeostasis could be vital to stomach health.


Nardone G & Compare D. (2015) The human gastric microbiota: Is it time to rethink the pathogenesis of stomach diseases? United European Gastroenterology Journal DOI: 10.1177/2050640614566846