Hydrogen (H2) is one of the gases produced in the intestinal lumen by bacteriological breakdown of carbohydrates. However, many studies have shown that approximately 30% of patients produce methane (CH4). Detection of both gases is complementary and it helps people to know about their digestive problems. It is also important to measure carbon dioxide (CO2) in the breath to determine whether the breath samples that are being analyzed are not contaminated either with room air or bronchial dead space air.