Nutritional Consequences of Small Intestinal Bacterial Overgrowth

15 INTRODUCTION Small intestinal bacterial overgrowth (SIBO) is characterized by a variety of signs and symptoms resulting from nutrient malabsorption when food, enteral feedings, medications such as lactulose or those containing sorbitol or fiber supplements interact with the bacteria. The symptoms may appear minor and nonspecific and lead to diagnostic confusion as these same signs and symptoms are often associated with an underlying disease process when present. SIBO implies a quantitative assessment of bacteria present in the small intestine. Although a certain level of commensal bacteria is important, it is the presence of a particular species type in an atypical location of the bowel, in addition to an excess number, that results in the development of the classical clinical manifestations of this condition. SIBO is usually defined as the presence of >105 colony forming units (cfu)/mL of bacteria in the proximal small intestine (1); however, it has been suggested that a lower colony count (e.g., >103 cfu/mL) may be adequate to induce symptoms as Nutritional Consequences of Small Intestinal Bacterial Overgrowth NUTRITION ISSUES IN GASTROENTEROLOGY, SERIES #69