Lactose intolerance

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Lactose intolerance is a common digestive disorder in which the body is unable to digest lactose, a sugar found in milk and dairy products. It is caused by a deficiency of the enzyme lactase, which is responsible for breaking down lactose into simpler sugars that can be easily absorbed into the bloodstream.


  • Lactose intolerance is caused by a deficiency of the enzyme lactase, which is produced by the cells lining the small intestine. Normally, lactase breaks down lactose into glucose and galactose, which are then absorbed into the bloodstream. When lactase is deficient, lactose remains undigested and passes through the digestive system. This can cause a range of symptoms, including bloating, gas, and diarrhea.
  • There are two main types of lactose intolerance:
  • Primary lactose intolerance: This is the most common type of lactose intolerance and is caused by a natural decrease in lactase production as we age. Primary lactose intolerance is more common in people of Asian, African, and Hispanic descent.
  • Secondary lactose intolerance: This type of lactose intolerance is caused by damage to the small intestine, such as from an infection, surgery, or other digestive disorder.


  • The symptoms of lactose intolerance can vary from person to person, and can range from mild to severe. Some common symptoms include:
  • Bloating
  • Gas
  • Abdominal pain or cramps
  • Diarrhea
  • Nausea
  • Symptoms typically occur within 30 minutes to two hours after consuming milk or dairy products.


  • Lactose intolerance can be diagnosed through a variety of tests, including:
  • Lactose tolerance test: This test involves drinking a liquid that contains lactose and then measuring the level of glucose in the blood over time.
  • Hydrogen breath test: This test measures the level of hydrogen in the breath after drinking a liquid that contains lactose.
  • Stool acidity test: This test measures the level of lactic acid in a stool sample after consuming lactose.


The primary treatment for lactose intolerance is to avoid or limit foods that contain lactose. This includes milk and dairy products, as well as some processed foods that contain lactose as an ingredient. People with lactose intolerance may also benefit from taking lactase supplements, which can help break down lactose and prevent symptoms.

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