Breath Test Symptoms Help Predict Lactose Intolerance in Adults
- Authors
- Davide G Cassella, Nunzio Zignani, Carolina Cavazzuti, Barbara Rossi, Alessandra Dell'Era, Giovanni Maconi
- Journal
- Clinical Nutrition ESPEN
- Year
- 2025
- DOI
- 10.1016/j.clnesp.2025.11.151
- Study Type
- Human
- Outcome
- Positive
- Peer Reviewed
- Yes
- Country
- Italy
- Health Condition
- Lactose Intolerance
- Body System
- Digestive
TL;DR
Flatulence during lactose breath testing strongly predicts lactose malabsorption, and adding methane measurement improves diagnostic accuracy.
Key Finding
Flatulence experienced during lactose breath testing was the strongest symptom predictor of lactose malabsorption, and people with severe symptoms (rated 6 or higher on a pain scale) were significantly more likely to be malabsorbers than those with mild symptoms.
Summary
This study looked at whether symptoms people experience during a lactose breath test (a test that measures gases produced when the body can't digest lactose) can predict lactose malabsorption—when the body struggles to break down lactose, a sugar in milk. Researchers tested 199 adults and found that flatulence (gas) during the test was the best symptom for predicting malabsorption, and people who experienced severe symptoms were more likely to be malabsorbers. The study also found that measuring methane gas in addition to hydrogen gas improved the accuracy of the test.
Practical Takeaway
If you're being tested for lactose malabsorption, paying attention to which symptoms you experience during the test—especially gas—may help doctors better understand your results. This study suggests that a more complete testing approach that measures both hydrogen and methane gases, combined with careful symptom tracking, may provide more accurate diagnosis than hydrogen measurement alone, potentially helping avoid unnecessarily strict dairy avoidance. However, this is a single study in adults with existing digestive symptoms, so results may not apply to everyone.
Abstract (excerpt)
Background/objective: Lactose malabsorption (LM) is common, yet not all malabsorbers develop lactose intolerance (LI). We aimed to assess whether symptoms recorded during the hydrogen breath test (HBT) predict LM and whether methane (CH4) measurement adds diagnostic information. Methods: In this…