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What is Lactose Intolerance?

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What is Lactose Intolerance?

Get the facts on lactose intolerance, the importance of a proper medical diagnosis, and how you can still get the nutrients your body needs after you’ve been diagnosed.

Milk contains a natural sugar called lactose. People who have lactose intolerance don't produce enough lactase (an enzyme) in their digestive tract in order to digest large amounts of lactose at one time. Without enough lactase enzyme, lactose builds up in the colon and causes symptoms such as gas, bloating and cramps. Lactose intolerance is not a milk allergy.

The United States’ foremost health authority weighs in

The National Institutes of Health (NIH), the United States' leading medical research agency, has indicated that it is difficult to estimate the number of people who suffer from lactose intolerance because of the many variables involved. NIH also says that most people who suffer from lactose intolerance may still continue to consume milk products. After all, humans lack the enzyme needed to digest complex sugars in beans and we can still eat them.

Since lactose intolerance is currently such a widely discussed topic, more and more people tend to assume that their digestive problems are due to lactose intolerance, even without a proper diagnosis. The symptoms of lactose intolerance are similar to those caused by other digestive disorders, so, a proper medical diagnosis is essential.

According to the NIH, adults and adolescents who exclude milk products from their diets are depriving themselves of an easily accessible source of calcium, vitamin D and other nutrients. As a result, this may increase the risk of osteoporosis in people who are already at the greatest risk, particularly women of all ages.

Did you know?

  • Most people who are lactose intolerant can still tolerate a small amount of lactose in their diet. In most cases, it’s not necessary to completely eliminate milk products.
  • Research shows that many people who have been clinically diagnosed as lactose intolerant report having no problems digesting 1 cup of milk (250 mL), which corresponds to 12 grams of lactose, especially when served with a meal or other foods.
  • Lactose intolerance is genetic.
  • Temporary lactose intolerance can be a side effect of certain conditions such as stomach flu, medication and food poisoning. When the condition passes or the medication is terminated, the intolerance goes away.
  • The ability to digest lactose often increases during pregnancy.

Read food labels

Lactose can be found in prepared foods and in some medications. Scan the ingredient list for terms such as milk powder, milk solids, whey and lactoserum - they indicate that the product contains lactose. But remember, the amount of lactose found in processed foods is quite small and not usually enough to cause symptoms. If you are concerned about the lactose content of a medication, talk to your pharmacist.


National Institutes of Health. NIH Consensus Development Conference Statement: Lactose Intolerance and Health. NIH Consens State Sci Statements 2010;27(2).

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