Breath tests offer a non-invasive approach to investigating various stomach-related issues. These tests analyze gases produced in the digestive tract and exhaled through the breath. They serve as a diagnostic tool for identifying conditions that affect digestion and nutrient absorption.
What Stomach Breath Tests Are
A breath test for stomach conditions is a medical procedure designed to detect specific gases in exhaled breath, which can indicate underlying digestive problems. The core purpose is to identify byproducts of bacterial activity or maldigestion that manifest as altered gas levels. Unlike more invasive methods, breath tests involve simply collecting breath samples over a period, making them a comfortable and accessible option.
These tests rely on the principle that digestive imbalances lead to the production of gases like hydrogen, methane, or carbon dioxide, which can be measured in the breath. The presence and concentration of these gases provide clues about how the digestive system is functioning. Analyzing these exhaled gases helps healthcare providers gain valuable information about a person’s gut health and pinpoint specific issues causing digestive discomfort.
Conditions Diagnosed by Breath Tests
Breath tests diagnose several gastrointestinal conditions. The Urea Breath Test detects Helicobacter pylori (H. pylori) infection, a bacterium known to cause gastritis, stomach ulcers, and peptic ulcer disease. This test identifies a specific enzyme produced by H. pylori in the stomach.
Small Intestinal Bacterial Overgrowth (SIBO) is diagnosed using Lactulose or Glucose Breath Tests. SIBO occurs when there is an excessive amount or an abnormal type of bacteria in the small intestine, leading to symptoms like bloating, gas, and abdominal pain. These tests measure hydrogen and methane gases produced by bacteria fermenting sugars in the small intestine.
Lactose intolerance, the inability to properly digest lactose found in dairy products, is identified through a Lactose Breath Test. When lactose is not broken down in the small intestine, it travels to the large intestine where bacteria ferment it, producing hydrogen gas. Similarly, Fructose intolerance, where the body struggles to absorb fructose, a sugar found in fruits and some vegetables, can be diagnosed with a Fructose Breath Test. Undigested fructose also leads to gas production by gut bacteria.
The Science Behind Breath Tests
The scientific basis of breath tests involves introducing a “tracer” substance, metabolized by human enzymes or gut bacteria. For conditions like SIBO or carbohydrate malabsorption, the patient ingests a measured amount of a sugar, such as lactulose, glucose, lactose, or fructose. If the body cannot properly digest or absorb these sugars, or if there is bacterial overgrowth, the unabsorbed sugar reaches gut bacteria.
These gut bacteria ferment the unabsorbed carbohydrates, producing gases like hydrogen and methane. These gases are absorbed into the bloodstream from the intestines, carried to the lungs, and then exhaled. Collected breath samples are analyzed using specialized equipment to measure gas levels in parts per million (ppm).
For H. pylori infection, the principle differs. The patient ingests a solution containing urea labeled with a carbon isotope. If H. pylori is present, it produces an enzyme called urease, which breaks down the labeled urea into ammonia and labeled carbon dioxide. This labeled carbon dioxide is absorbed into the bloodstream and exhaled, indicating the bacteria’s presence.
Preparing for Your Breath Test
Preparation is important for accurate breath test results. Individuals typically fast for a specific period, often 12 hours, before the test, consuming only water. Avoiding smoking or vigorous exercise for at least an hour before and during the test is also recommended.
Certain medications can interfere with test results and must be stopped in advance. Antibiotics and probiotics are often discontinued for a period ranging from one week to one month prior to the test to prevent alterations in gut bacteria. Proton pump inhibitors (PPIs) and bismuth-containing medications may also need to be avoided for a specified duration, typically two weeks before the test, especially for H. pylori tests.
A specific diet, often referred to as a “low-residue” or “white diet,” is frequently recommended for 24 hours before the test. This diet limits foods that are difficult to digest or that can ferment in the gut, such as high-fiber foods, fruits, vegetables, and certain sugars. During the test, after a baseline breath sample is collected, the patient drinks a prepared solution. Breath samples are then collected at regular intervals, often every 15-30 minutes, over a period of two to four hours by breathing into collection bags or tubes.
Interpreting Breath Test Results
Interpreting breath test results involves comparing baseline gas levels with levels measured after ingesting the test substance. For hydrogen and methane breath tests, a significant rise in gas concentration above baseline indicates a positive result. For instance, a rise in hydrogen by 20 parts per million (ppm) from baseline after lactose ingestion suggests lactose malabsorption. Similarly, a rise of 20 ppm or more within 90 minutes after lactulose ingestion can indicate SIBO.
A positive result means the body is either not properly digesting the ingested sugar or bacteria are overgrowing and fermenting the sugar. In the case of the H. pylori urea breath test, a higher amount of labeled carbon dioxide in the second breath sample compared to the first indicates the presence of H. pylori bacteria. Conversely, little to no change in gas levels suggests a negative result. A healthcare professional should always interpret these results in conjunction with a person’s symptoms and medical history to formulate an accurate diagnosis and treatment plan.