Gas in the digestive tract is not a subject that most people like to talk about, but the truth is that all of us have it and must get rid of it in some way. Normally, the gas passes out through the rectum or is belched through the mouth. These are both necessary functions of the body that allow us to eliminate gas. When gas does not pass out of the body easily, it can collect in some part of the digestive tract, causing bloating and discomfort. Even normal amounts of gas in the body can bother people who are sensitive to this pressure. Although gas usually is not a sign of a medical problem, it can be. So if you have persistent or extreme gassiness (flatulence), mention it to your doctor when you have a checkup.
A common source of upper intestinal gas is swallowed air. Each time we swallow, small amounts of air enter the stomach. This gas in the stomach is usually passed into the small intestine where part of it is absorbed. The rest travels into the colon (large intestine) to be passed out through the rectum. In some people, part of the gas is belched out instead of being passed from the stomach into the intestine. This happens for several reasons. People under a lot of stress often swallow large amounts of air. Some people swallow air frequently because they have post-nasal drip, chew gum, or smoke. Rapid eating or poorly fitting dentures also may cause too much air to be swallowed. Also, drinking beverages that contain carbonated water may increase gas in the digestive tract. These drinks contain carbon dioxide, which can produce large amounts of gas when warmed in the stomach. People with a gas problem should avoid carbonated or "sparkling" drinks.