Lactose intolerance: how it is diagnosed and treated
What it found
Lactose intolerance is common worldwide, affecting between 57% and 65% of people.
It happens when the gut makes less lactase, the enzyme that digests lactose.
What they found
Studies in people
How common it is
Lactose intolerance is common worldwide, with prevalence ranging between 57% and 65%.
Symptoms and their cause
The change raises the osmotic load in the small intestine and lets gut bacteria ferment lactose, producing short-chain fatty acids and gas. This leads to abdominal pain, diarrhea, and flatulence.
Other conditions
People with lactose intolerance were found to have an increased risk of developing various extra-intestinal diseases, including cancers.
Other findings
What causes it
It is caused by a reduction or loss of activity of the intestinal enzyme lactase-phlorizin hydrolase, which is responsible for digesting lactose.
Diagnosis methods
Methods tested include genetic test, hydrogen breath test (HBT), quick lactase test, and lactose tolerance test. HBT is the most used because it is non-invasive, inexpensive, highly sensitive and specific, and easy to perform.
Treatment options
Options include eating lactose-free foods with nutritional characteristics comparable to dairy products, using exogenous enzymes, probiotics, prebiotics, and selecting milk containing specific types of beta-caseins.
What the authors conclude
“Lactose intolerance has a high prevalence worldwide, ranging between 57% and 65%.”
Also in their conclusions
- They state that the diagnosis is essential to undertake an adequate treatment.
- They note that in clinical practice, the other methods are mainly used as HBT integration tests.
- They say an appropriate intervention concerns the dietetic style, such as the consumption of lactose-free foods, but with nutritional characteristics comparable to dairy products.
How it was done
The authors wanted to set out the diagnostic methods and treatment options currently available for lactose intolerance.
What it can’t tell you
- We summarised it from the abstract only.
- This is a review of existing information, not a new study in people.
- It cannot show whether treating lactose intolerance lowers the risk of the extra-intestinal diseases mentioned.
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 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error