Small bowel bacterial overgrowth (SBBO), an increasingly recognized malabsorptive condition caused by the excessive growth of bacteria in the small bowel, results in a spectrum of symptoms such as diarrhea, bloating abdominal discomfort and weight loss. Multiple factors both internal and external to the individual prevent excessive small bowel bacterial colonization and determine the types of bacteria present. The most important factors within the individual are normal small bowel motility, which prevents attachment of ingested organisms, and gastric acid, which destroys many organisms before they reach the small intestine. The determination of small bowel motility is problematic due to limitations of the tests available (e.g., hydrogen breath test, scintigraphy and manometry).