Lactose Intolerance

If you’ve ever felt a foreboding rumbling in your stomach shortly after eating, you may have wondered whether you’re lactose intolerant. Lactose is a type of sugar found in milk products. Some people are unable to digest it properly, leading to unpleasant digestive symptoms after dairy intake.

What is lactose intolerance?

  • Lactose intolerance is a digestive disorder caused by the inability to digest lactose, the main carbohydrate in dairy products. It’s very common, affecting around two-thirds of the world’s adult population at minimum.

  • This condition occurs if your body doesn’t make enough of the enzyme lactase, which you need to digest lactose.

  • People with lactose intolerance experience digestive problems when they consume dairy, which can negatively affect their quality of life.

  • These symptoms include bloating, diarrhea, and abdominal cramps.

Who is affected?

  • For most people, lactose intolerance develops over time as the body produces less lactase.

  • It is estimated that 36% of Americans and 68% of the world population have some degree of lactose intolerance.

  • Lactose intolerance affects people from certain ethnic populations and races—such as Latin Americans, African-Americans, Native Americans, Asians, East Europeans and Middle Easterners—more than others.


  • Lactose intolerance is caused by a shortage of lactase in the body, an enzyme produced by the small intestine that is needed to digest lactose.

  • Certain digestive diseases (such as Crohn’s disease, ulcerative colitis, and celiac disease), stomach or intestinal infections, and injuries to the small intestine (such as surgery, trauma, chemotherapy, or radiation therapy) may reduce the amount of lactase available to process lactose properly.

  • If the small intestine is injured, lactose intolerance may be temporary, with symptoms improving after the intestine has healed.


  • Symptoms of lactose intolerance include nausea, cramps, gas, bloating, or diarrhea within 30 minutes to 2 hours after consuming milk or dairy products.

  • Symptoms occur because there is not enough lactase being produced by the body to digest the lactose consumed.

  • The severity of symptoms varies, depending on the amount of lactose an individual person can tolerate.

  • Some people may be sensitive to extremely small amounts of lactose-containing foods while others can eat larger amounts before they notice symptoms.


  • The most common test for the diagnosis of lactase deficiency is the hydrogen breath test.

  • This test is done at an outpatient clinic or doctor’s office.

  • In practice, many doctors will ask patients who suspect they have lactose intolerance to avoid milk and dairy products for 1 or 2 weeks to see if their symptoms subside, and will then confirm the diagnosis with the hydrogen breath test.

  • The hydrogen breath test measures the amount of hydrogen in the breath after drinking a lactose-loaded beverage.


  • Lactose intolerance is easily treated. The goal of treatment is to control symptoms through dietary changes.

  • People with lactose intolerance can usually find a level of lactose-containing foods that will not produce symptoms.

  • You can learn through trial and error what amount and type of lactose-containing products you can tolerate or you can temporarily eliminate all lactose-containing foods from your usual diet using a Lactose-Free Diet, then gradually add them back to find your level of tolerance and comfort.

  • For trial and error, try having smaller portions of your usual dairy foods, substituting them with lactose-free dairy products, or consuming milk and dairy products with meals because lactose may be better tolerated when eaten with other foods.

  • Further, you may be may notice better tolerance of certain dairy foods that contain lower amounts of lactose, such as cheese, yogurt and cottage cheese.

diseases treatments health prevention digestive-system lactose-intolerance

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