Lactose intolerance, how it is diagnosed and treated
What it found
Between 57% and 65% of people worldwide have lactose intolerance.
A breath test is the most common way to diagnose it, and options like lactose-free foods or enzyme supplements can help manage symptoms.
What they found
Studies in people
How common it is
Between 57% and 65% of people around the world have lactose intolerance.
What causes symptoms
When the gut enzyme that breaks down lactose is low or missing, extra water is drawn into the small intestine. Gut bacteria then ferment the undigested lactose, producing gas and short-chain fatty acids. This leads to belly pain, loose stools, and wind.
Other health risks
People with lactose intolerance were found to have a higher chance of developing diseases outside the gut, including cancers.
Other findings
Diagnosing the condition
A hydrogen breath test is the most widely used method because it is cheap, easy, non-invasive, and accurate. Genetic tests, quick lactase tests, and lactose tolerance tests are also available but are mostly used alongside the breath test.
Managing the condition
Treatment options include eating lactose-free foods with similar nutrition to dairy, taking enzyme supplements, using probiotics or prebiotics, or choosing milk made with specific types of beta-casein proteins.
What the authors conclude
- They set out to explain the diagnostic methods currently available for lactose intolerance.
- They also describe the possible treatment choices people can use to manage the condition.
How it was done
The authors wanted to outline the current ways to diagnose lactose intolerance and the treatments available for managing it.
They gathered and summarised existing research on what causes lactose intolerance, how doctors test for it, and what treatments are used. The abstract does not state how many studies were included or over what time period.
What it can’t tell you
- We summarised it from the abstract only.
- This work gathers existing research rather than running a new trial, so it cannot prove that any single treatment works better than another.
- The link between lactose intolerance and other diseases like cancer comes from observed patterns, which cannot show that one causes the other.
Who paid
- Authors work at
- University of Catania, Italy
The paper
- Title
- Lactose intolerance: An update on its pathogenesis, diagnosis, and treatment
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Catanzaro R, Sciuto M, Marotta F (2021). Lactose intolerance: An update on its pathogenesis, diagnosis, and treatment. Nutrition research (New York, N.Y.). doi:10.1016/j.nutres.2021.02.003PubMed 33887513DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error