Intestinal Gas: Where It Comes From and What It May Indicate

Everyone has gas in the intestines, and it is not a diagnosis. The abdomen may feel full and rumble. Let us clarify where normal ends and when it becomes a reason for examination.

What intestinal gas is and where it comes from

Gas in the digestive tract forms from two sources: air that we swallow, and the breakdown of undigested food by bacteria in the colon. Gas exits through the mouth as belching and through the anus as flatulence. A healthy adult has about one liter of gas in the stomach and intestines, and 0.1–0.5 liters is expelled per day. The gas mixture includes nitrogen, carbon dioxide, oxygen, hydrogen, and methane, as well as a small amount of hydrogen sulfide, ammonia, and volatile mercaptans. With meteorism, the volume of expelled gas can reach three or more liters.

How much gas is considered normal

Most people pass gas 13–21 times a day. Usually it has no odor: the characteristic smell comes from trace sulfur compounds released by colon bacteria when breaking down protein. Increased gas formation may be a sign of dysbiosis, gastrointestinal diseases (pancreatitis, enteritis, colitis), acute intestinal infections, or helminthiases.

Causes of increased gas formation

Gas in the abdomen increases with foods high in carbohydrates, legumes, cabbage, apples, highly carbonated drinks, as well as foods that cause fermentation. In people with lactose intolerance, dairy products trigger a reaction. Some gas appears due to swallowing air while eating. Among medical causes of bloating are constipation, food intolerance, celiac disease, and irritable bowel syndrome. In some people, the abdomen bloats during menstruation. Persistent bloating that does not resolve can sometimes be a sign of a more serious disease, such as ovarian cancer.

Symptoms: bloating, foul-smelling gas, when gas does not pass

With meteorism, there may be belching, a feeling of distension and heaviness, cramping pain that resolves after passing gas, nausea, an unpleasant taste in the mouth, and decreased appetite. Bloating is a feeling of fullness and enlargement of the abdomen, rumbling, and discomfort. If gas does not pass at all, this is already a warning sign requiring medical evaluation. Blood in the stool or unintentional weight loss against a background of bloating should also raise concern.

• the abdomen feels full or larger than usual
• rumbling and sounds in the abdomen
• passing gas more often than usual
• pain or discomfort in the abdomen

Which examinations help find the cause

If dietary advice does not help, the doctor may refer you to a dietitian or to a specialist for tests to determine the cause of bloating.

When to see a doctor

You should make an appointment with a doctor if bloating occurs regularly, does not resolve with dietary changes, is combined with unintentional weight loss or blood in the stool. An urgent consultation is needed for bloating with vomiting, diarrhea or constipation, abdominal pain, high fever, swelling or a lump in the abdomen, inability to urinate, have a bowel movement, or pass gas, as well as burning behind the sternum due to acid reflux.

Bloating alone is not a reason to call an ambulance; 103 or 112 — if the abdomen is bloated and at the same time the abdominal pain is severe and came on suddenly, vomiting with blood or resembling coffee grounds, or severe difficulty breathing — the person is gasping and cannot speak.

This material is for reference: it helps you orient yourself but does not replace a doctor's consultation — for persistent complaints, it is better to discuss them at an appointment.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer