Lactose intolerance is one of the most common causes of digestive discomfort after consuming milk or dairy products. Symptoms such as bloating, gas, diarrhea, abdominal pain, or nausea may indicate that the body is not digesting this sugar properly.
The lactose breath test is a simple, non-invasive diagnostic test that evaluates how your intestine processes lactose and helps confirm whether lactose intolerance is present.
In this article, we explain how the test works, when it may be advisable to take it, and how to prepare properly.
What is lactose and why are some people intolerant to it?
Lactose is the natural sugar found in milk and many dairy products. To digest it properly, the small intestine requires an enzyme called lactase.
When the activity of this enzyme is insufficient, lactose is not properly digested and passes into the colon. There, intestinal bacteria ferment it and produce gases such as hydrogen and methane, which are responsible for many digestive symptoms.
In most people, lactase production decreases with age. In fact, it is estimated that approximately 75% of the world's adult population has some degree of primary lactose intolerance. This type of intolerance is usually genetic in origin and is more common in certain ethnic groups.
How does the lactose breath test work?
The lactose breath test measures the amount of hydrogen and/or methane present in the air you exhale after drinking a lactose-containing solution.
The procedure is as follows:
- An initial breath sample is collected.
- The patient drinks a solution containing lactose.
- Additional breath samples are collected at regular intervals over several hours.
- The laboratory analyzes the gases produced by bacterial fermentation.
If hydrogen or methane levels increase significantly during the test, this may indicate lactose malabsorption.
It is a safe, non-invasive test that is widely used in gastroenterology to confirm a diagnosis of lactose intolerance.
When may this test be recommended?
The lactose breath test may be useful if you experience digestive symptoms after consuming dairy products, such as:
- Abdominal pain or cramps
- Bloating or abdominal distension
- Frequent gas
- Diarrhea after consuming milk or dairy products
- Nausea or digestive discomfort
It may also be recommended when a healthcare professional suspects lactose intolerance and wishes to confirm the diagnosis before making significant dietary changes.
Having a clear diagnosis makes it possible to adapt your diet appropriately, avoid unnecessary restrictions, and maintain a balanced diet.
How to prepare for the breath test
Proper preparation is essential to obtain reliable results. Before the test, it is important to follow several recommendations.
In general, it is recommended to:
- Fast for at least 12 hours before the test.
- Avoid taking antibiotics during the previous 4 weeks, as they can alter the intestinal microbiota.
- Avoid probiotics, fiber supplements, and laxatives for at least one week beforehand.
- Follow a low-residue diet during the 24 hours prior to the test.
- Avoid smoking and strenuous exercise before and during the test.
In addition, the testing center will provide a specific preparation guide that should be read carefully.
When will you receive the results?
Once the analysis has been completed, results are usually available within approximately 7 business days.
You will receive a notification by SMS or email when your report is available in the online Patient Portal, where you can view and download it securely.
It is advisable to review the results with a healthcare professional, who can interpret them correctly and help you establish a nutritional plan tailored to your situation if necessary.
Why is it important to confirm lactose intolerance?
Many people eliminate dairy products from their diet because they suspect lactose intolerance, but this is not always necessary. An accurate diagnosis allows you to:
- Determine whether lactose intolerance is actually present.
- Identify your individual level of lactose tolerance.
- Avoid unnecessary dietary restrictions.
- Improve digestive symptoms with a personalized diet.
The lactose breath test is an effective tool for resolving doubts and better understanding how your body responds to this common dietary component.