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Lactose Intolerance

The inability to digest or absorb lactose, a type of sugar found in milk and other dairy products.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Lactose Intolerance

Stomach ache, bloating, "gas" and diarrhea are all typical digestive symptoms that some people have after eating or drinking dairy products. People who have difficulty digesting dairy products may only tolerate small amounts of lactose (a sugar found in milk and other dairy products). This is called lactose intolerance.

But some people who are sensitive to milk might actually have a different problem. It is important to get the diagnosis right before deciding to make major changes to your diet, especially in children, teenagers and people who need more calcium.

Lactose intolerance is not an allergy. This is an important difference. People who have a true milk allergy can react to even a tiny amount of dairy foods or milk. But people who are lactose intolerant can sometimes consume quite a lot of these products without having any major problems... Read more about Lactose Intolerance

What works? Research summarized

Evidence reviews

Lactose Intolerance and Health

We systematically reviewed evidence to determine lactose intolerance (LI) prevalence, bone health after dairy-exclusion diets, tolerable dose of lactose in subjects with diagnosed LI, and management.

Do probiotics reduce adult lactose intolerance: a systematic review

PURPOSE: To assess the efficacy of oral probiotics in adults with lactose intolerance through a systematic review of its effects on symptoms and breath hydrogen tests, and whether adding probiotics to nonfermented dairy products decreases lactose intolerance at that meal.

Lactose malabsorption and intolerance: a systematic review on the diagnostic value of gastrointestinal symptoms and self-reported milk intolerance

BACKGROUND: When lactose malabsorption gives rise to symptoms, the result is called 'lactose intolerance'. Although lactose intolerance is often bothersome for patients, once recognized it may be managed by simple dietary adjustments. However, diagnosing lactose intolerance is not straightforward, especially in primary care.

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Summaries for consumers

Living with lactose intolerance

People who have lactose intolerance are still able to eat and drink small amounts of dairy products - preferably together with other foods. So far there is no conclusive proof that lactase products and probiotic nutritional supplements help to digest lactose better.Most people with lactose intolerance have no or almost no symptoms when they ingest small amounts of lactose. Symptoms can also be milder if the dairy products are consumed together with other foods. That is because solid or fatty foods slow down the digestion process in the stomach. Less lactose then enters the intestine in one go, and the intestine reacts less sensitively.Research has indicated that some people can tolerate lactose better if they carefully and gradually increase the amount of lactose in their diet. But this has not been tested enough yet.

Causes and diagnosis of lactose intolerance

Some people have digestive problems after drinking milk or eating dairy products. They may only tolerate very small amounts of lactose because their bowel has trouble breaking it down.Lactose is the main carbohydrate in milk produced by cows and other animals. Human breast milk also contains lactose. It is not present in vegetable products like soy milk. Lactose consists of two sugars: glucose and galactose. An enzyme in our small intestine called lactase quickly breaks down the lactose into its two parts. Only after the two sugars have been separated can they be absorbed by our bowel.

Lactose intolerance: Overview

Stomach ache, bloating, "gas" and diarrhea are all typical digestive symptoms that some people have after eating or drinking dairy products. People who have difficulty digesting dairy products may only tolerate certain amounts of lactose (a sugar found in milk and other dairy products). This is called lactose intolerance.

See all (7)

Terms to know

Diarrhea
Frequent, loose, and watery bowel movements. Common causes include gastrointestinal infections, irritable bowel syndrome, medicines, and malabsorption.
Digestion
The process of breaking down food into substances the body can use for energy, tissue growth, and repair.
Enzymes
Protein made by the body that brings about a chemical reaction - for example, the enzymes produced by the gut to aid digestion.
Lactase
An enzyme in the small intestine needed to digest milk sugar (lactose).
Lactose
A type of sugar found in milk and milk products.
Nausea
A feeling of sickness or discomfort in the stomach that may come with an urge to vomit.

More about Lactose Intolerance

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Also called: Cow's milk enteropathy, Lactose malabsorption

Other terms to know: See all 6
Diarrhea, Digestion, Enzymes

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