Hi, Lower intestinal gas is the normal byproduct of bacterial action on food that is not broken down until reaching the colon. Intestinal gas related to bacterial action is made up of hydrogen, carbon dioxide and sometimes methane. Foods that cause gas  Some foods contain substances that aren't fully digested until they are acted upon (metabolized) by the bacteria in the lower intestine, where they're broken down into simpler substances, including gas. Common gas-producing foods and substances include: Beans and lentils Dairy products containing lactose Fructose and sorbitol, which are found in some fruits and are also used as sweeteners Digestive disorders that cause gas: IBS, celiac disease, gastroparesis, peptic ulcer, dumping syndrome..