Breath tests. Can be used to diagnose several conditions: H pylori infection, lactose intolerance and small intestinal bacterial overgrowth (SIBO). Testing for SIBO, often used in testing for irritable bowel syndrome, measures gases in expired air over a period of 2-5 hours (requires fasting 8-12 hr prior to test). Testing for H. pylori can be preformed after 1 hour of fasting, and required only about 10 min.
Same thing. A hydrogen breath test, which measures hydrogen & methane gas produced by bacteria, is used to diagnose several conditions: SIBO, H pylori infection, carbohydrate malabsorption. Hope that helps.