SIBO is a condition where abnormally large numbers of bacteria grow in the small intestine. In addition, the types of bacteria may change and resemble those found normally in the large intestine (e.g. Gram negative bacteria and anaerobes). Under normal circumstances, the small intestine contains a relatively low number of bacteria (less than 10,000 bacteria per ml) whereas the large intestine contains much larger numbers of bacteria (more than 1,000,000,000 bacteria per ml). Overgrowth of bacteria in the small intestine may occur in a number of diseases, such as Crohn’s disease, diabetes, scleroderma, diverticulosis or following surgery. In addition, some doctors believe that some people with irritable bowel syndrome also suffer with SIBO. The most common symptoms of SIBO are abdominal fullness or bloating, abdominal pain or cramps, or diarrhoea (usually watery). Other symptoms may include fatty stool (more smelly and more difficult to flush away), nausea and weight loss. SIBO can be diagnosed by the hydrogen breath test.