Lactose intolerance, dairy avoidance and treatment options
What it found
Most people who maldigest lactose can still handle the lactose in a cup of milk, and cutting out dairy entirely is not recommended.
The paper reviews the genetics, symptoms and treatments, and the health effects of dairy in people.
What they found
Studies in people
How much lactose is tolerated
Most lactose maldigesters can handle the lactose in a cup of milk (12.5 g in 250 mL) with minimal to no symptoms. Most people with lactose intolerance can tolerate up to 12 to 15 grams of lactose per day.
Self-reported intolerance unreliable
In a meta-analysis of 21 studies comparing lactose with placebo in people with gut symptoms, abdominal symptoms differed minimally or not at all between the groups. A systematic review of 26 studies found symptoms were a highly variable predictor of malabsorption, and both absorbers and maldigesters reported symptoms during testing.
Lactose in medicines
In a controlled trial using breath tests, the lactose in medicines (average 400 mg) did not raise breath hydrogen, suggesting it was absorbed. This amount is far below the 10 to 15 g tolerated by lactase-persistent people.
Dairy and bone health
A review of 52 randomized and 89 observational studies concluded that dairy foods are an excellent source of nutrients for healthy bone. A study of dairy restriction in girls aged 10 to 13 found about a 210 mg calcium intake deficit compared with girls without self-reported lactose intolerance.
Dairy and heart and diabetes
A large systematic analysis found dairy had a neutral effect on cardiovascular disease and coronary artery disease, with a modest inverse link for stroke. High-quality evidence supports that low-fat dairy and yogurt reduce risk for type 2 diabetes.
Dairy and cancers
Observational studies consistently show colon cancer is inversely associated with dairy intake. Meta-analyses support an enhancing effect of dairy foods on prostate cancer, and total dairy and milk were found to pose an almost two-fold risk for non-Hodgkin's lymphoma.
Plant-based substitutes
A Canadian study reported that consumption of plant-based drinks was associated with lower childhood height. Only cow's milk and fortified soy beverage are considered nutritious enough for children aged 1 to 8.
Lactase enzyme tablets
In a study of 96 people who were genetically lactase deficient, two lactase tablets containing 7500 IU were used with 25 g lactose in water. About 22% became negative on breath testing, about 18% had a significant reduction, and the rest showed no significant difference from baseline.
What the authors conclude
“The avoidance of all dairy products in patients with lactose intolerance is no longer recommended.”
Also in their conclusions
- They say that withholding dairy foods completely is not appropriate due to a more favorable impact on health.
- They advise that people with lactose intolerance should be encouraged to restrict rather than avoid lactose, with the goal of including some dairy foods in the diet.
- They call for the food industry to improve product labels and for government to standardize the definition of "no lactose" and "reduced lactose" and make lactose content mandatory on nutrition labels.
How it was done
The authors wanted to sort out the confusion between lactose maldigestion and the symptoms people call lactose intolerance, and to look at whether avoiding dairy is the right response.
They reviewed published studies on the genetics, diagnosis and symptoms of lactose intolerance, on treatments such as lactose-reduced products, plant-based substitutes, enzymes, prebiotics and probiotics, and on how dairy foods relate to 19 common diseases.
What it can’t tell you
- The review draws on many different study types, so it cannot show cause and effect for the disease links it describes.
- Some of the findings come from animal and lab studies, which cannot show what happens in people.
- The authors note that the reasons for discrepancies between observational studies and genetic studies are not absolutely clear.
Who paid
- Conflicts
- The authors declare no interests of conflict.
- Authors work at
- McGill University School of Medicine, Canada
The paper
- Title
- Lactose Intolerance, Dairy Avoidance, and Treatment Options
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Szilagyi A, Ishayek N (2018). Lactose Intolerance, Dairy Avoidance, and Treatment Options. Nutrients. doi:10.3390/nu10121994Free full textPubMed 30558337DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error