But if they are severe or troublesome and if you are worried about them you should seek the help of your doctor. The colon acts as a gas works. It contains a huge population of many different kinds of bacteria which are essential to good health and which ferment the residues delivered from the small intestine, producing large volumes of hydrogen, methane, carbon dioxide and other gases in the process. Every time we swallow we take some air into the stomach. Eating rapidly or gulping food and drink, drinking a lot of liquid with meals, chewing gum, smoking, or wearing loose dentures promote air swallowing.
Some people swallow saliva to relieve heartburn and swallow air at the same time.
Other people swallow air without noticing it, especially when they are tense. In this case air is not swallowed into the stomach but sucked into the gullet and rapidly expelled. Repetitive belching like this can last for minutes at a time and is very embarrassing. It is nearly always due to stress or anxiety. Air cannot be sucked in when the jaws are separated, so repetitive belching can be temporarily controlled by firmly clenching something like a pencil between the teeth.