Purpose of review: To highlight the recent studies which have enhanced our appreciation of the composition of the microbiota in the human small intestine and its relevance to the health of the host.
Recent findings: In the past number of years, the composition of the microorganisms present in our small intestines has been the subject of greater scrutiny than ever before. These investigations have been possible as a consequence of the development and utilization of new molecular tools which have revolutionized the field of microbial ecology and have focused predominantly on the small intestinal microbiota associated with pediatric celiac disease, inflammatory bowel disease, irritable bowel syndrome and pouchitis. The impact of invasive procedures, such as small bowel transplant, ileostomy and ileal pouch anal anastomosis, on the ileal microbiota has also been investigated.
Summary: The ever greater appreciation of the link between the small intestinal microbiota and the health status of the host has the potential to lead to the development of new strategies to alter this microbiota in a targeted way to prevent or treat specific disorders.