Gas is a natural by-product of the digestive process, but it can sometimes cause discomfort and embarrassment. This guide will help you understand the causes, symptoms, and ways to diagnose issues related to gas.

What Is Gas and How Is It Formed?

Gas is a normal part of digestion, and most individuals produce between 1 and 4 pints of gas each day, passing it around 14 times. The primary constituents of gas are odourless vapours such as carbon dioxide, oxygen, nitrogen, hydrogen, and occasionally methane. The odour typically associated with flatulence originates from bacteria in the large intestine, which produce trace amounts of sulphur-containing gases.

Key Causes of Gas

Digestive tract gas has two primary sources:

  1. Swallowed Air: Consuming food and beverages quickly, chewing gum, or even wearing loose dentures can result in the swallowing of small amounts of air, which is a frequent cause of stomach gas. This swallowed air primarily consists of nitrogen, oxygen, and carbon dioxide and is usually expelled through burping.
  2. Breakdown of Undigested Foods: Undigested carbohydrates in the small intestine are broken down by bacteria in the large intestine. These bacteria produce gases like hydrogen and carbon dioxide, and in some individuals, methane.

Common Symptoms and Problems of Gas


Occasional burping after meals is standard. However, persistent belching might indicate underlying gastrointestinal issues such as GERD or peptic ulcers.


While passing gas 14 to 23 times a day is considered normal, excess flatulence may result from poor carbohydrate absorption.

Abdominal Bloating

Often caused by intestinal disorders like irritable bowel syndrome (IBS), bloating can also be triggered by fatty foods or intestinal inflammation.

Abdominal Pain

The presence of gas can cause pain in the intestines, sometimes leading to confusion with other conditions like heart disease or gallstones.

Diagnostic Breath Tests for Gas Issues

Breath tests are non-invasive diagnostic tools used to identify the cause of gas and related symptoms. These tests include:

Lactose Intolerance Breath Test

This test helps diagnose the inability to digest lactose found in dairy products.

Fructose Intolerance Breath Test

This test identifies fructose absorption issues, symptoms of which include gas and bloating.

Bacterial Overgrowth Syndrome (SIBO) Test

Used to diagnose uncontrolled bacteria growth in the small intestine, causing symptoms like excessive gas and bloating.

Understanding the causes and symptoms of gas can help in finding relief and proper treatment for this common but often misunderstood condition.