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Causes and diagnosis of lactose intolerance

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Lactose intolerance results from the body not producing enough lactase. Without this enzyme, lactose can’t be properly digested. Lactose intolerance is usually genetic (passed on to children in their parents’ genes) but it can also arise from other diseases. Various tests are used to diagnose lactose intolerance, such as the hydrogen breath test.

Some people have digestive problems after drinking milk or eating products that contain lactose (the sugar in milk). They only tolerate very small amounts of lactose because their bowel has trouble breaking down larger quantities. This is called lactose intolerance.

Lactose is made up of two sugars: glucose and galactose. Our small intestine produces an enzyme called lactase. This enzyme breaks down the lactose into its two parts so that they can be absorbed by the bowel.

How does lactose intolerance develop?

What causes the symptoms of lactose intolerance?

What else could cause these symptoms?

How is lactose intolerance diagnosed?

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Updated on November 20, 2024

Next planned update: 2027

Publisher:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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