10 Things to Know About Lactose Intolerance

  • Woman holding milk
    1. It’s all in the enzymes.
    Normally, your body produces an enzyme called lactase. When you drink a glass of milk or eat cottage cheese, lactase helps you break down the milk sugar lactose into simpler sugars that are absorbed into your bloodstream. Lactose intolerance occurs when you have a lactase deficiency.

  • Doctor with clipboard
    2. You should involve your doctor.
    Some illnesses have stomach symptoms similar to those of lactose intolerance. Your doctor can help you pinpoint the cause of your complaints. He or she may start by asking you to remove all dairy from your diet to see if you feel better. Breath tests or tests of your stool can confirm the diagnosis.

  • Man holding stomach
    3. Not everyone has symptoms.
    Undigested lactose can produce a wide range of gastrointestinal symptoms within two hours of consuming dairy. These include bloating, nausea, flatulence, abdominal pain, and diarrhea. However, you can have a lactase deficiency and have no signs at all.

  • Boy with milk
    4. You usually grow into it.
    A few babies are lactose intolerant from birth and must drink lactose-free formula instead of breast milk. However, most people who are lactose intolerant lose their ability to digest milk sometime after infancy. Usually, this occurs between ages 2 and 12, though you may not experience symptoms until late adolescence or adulthood.

  • Happy family
    5. You’re not alone.
    As many as 65 percent of people worldwide, and 30 million Americans, have some degree of lactose intolerance. It’s more common if your background is Asian, African, Hispanic, or Native American, and less likely if your ancestors are from northern or western Europe.

  • Girl with allergies
    6. It’s not an allergy.
    Milk allergy is less common but more harmful than lactose intolerance. If you’re allergic to milk, your body fights dairy as if it were a harmful invader. Symptoms are typically more severe and can include wheezing, itchy eyes, and rash. People with this allergy must avoid milk products entirely.

  • Cheese
    7. Not all dairy is off limits.
    Unlike those with allergies, most people with lactose intolerance can drink up to a half-cup of milk with no symptoms. Other dairy products have lower levels of lactose and may be even easier to digest. These include hard or aged cheeses and yogurt.

  • Father and daughter at table with cereal
    8. Lactose appears in surprising places.
    Milk and milk products are added to a wide variety of processed foods. For instance, baked goods, cereals, and candies can all contain lactose. Check labels for the words whey, curds, and dry milk solids, and avoid these products if they aggravate your stomach.

  • Woman taking pill
    9. Dietary changes can relieve symptoms.
    Start with small doses of dairy and see if you can increase your intake over time. Lactose-free and reduced-lactose milk are increasingly available, as are soy milk and other milk substitutes. Finally, taking over-the-counter lactase drops or tablets can help you digest dairy.

  • Man cracking eggs
    10. Calcium is still key.
    Because dairy products are a major source of bone-strengthening calcium and vitamin D, lactose intolerance may increase your risk for thin bones. Eat other sources of calcium and vitamin D, including leafy greens, egg yolks, and fortified juices. And ask your doctor if you should take supplements.

10 Facts About Lactose Intolerance

About The Author

  1. Lactose Intolerance. National Digestive Diseases Information Clearinghouse. Apr. 23, 2012. http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/ 
  2. What I need to know about Lactose Intolerance. National Digestive Diseases Information Clearinghouse. May 10, 2012. http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance_ez/ 
  3. Lactose intolerance. U.S. National Library of Medicine. Jan. 1, 2013. http://ghr.nlm.nih.gov/condition/lactose-intolerance 
  4. Is Lactose-Free Milk Real Milk? Academy of Nutrition and Dietetics. 2012. http://www.eatright.org/Public/content.aspx?id=6442452714
  5. Is Lactose Intolerance the Same as a Milk Allergy? Academy of Nutrition and Dietetics. 2012. http://www.eatright.org/Public/content.aspx?id=8402 
  6. What People With Lactose Intolerance Need to Know About Osteoporosis. NIH Osteoporosis and Related Bone Diseases National Resource Center. Jan. 2012. http://www.niams.nih.gov/Health_Info/Bone/Osteoporosis/Conditions_Behaviors/lactose_intolerance.asp 
  7. Lactose intolerance. U.S. National Library of Medicine and the National Institutes of Health. Aug. 10, 2012. http://www.nlm.nih.gov/medlineplus/ency/article/000276.htm  
  8. Mattar R, et al Lactose intolerance: diagnosis, genetic, and clinical factors. Clinical and Experimental Gastroenterology. 2012;(5):113-21.
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Last Review Date: 2019 Jun 25
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