Can You Develop Lactose Intolerance?

You drank milk and ate dairy as a child and never had any problems, but you’ve recently started experiencing stomach cramps, bloating, or other common symptoms of lactose intolerance after eating dairy. This isn’t uncommon; you are more likely to develop lactose intolerance as you get older.

It's uncommon for babies and young children to have lactose intolerance. Most lactose intolerance develops in adulthood. Click To Tweet

What is lactose intolerance?

People with lactose intolerance are unable to digest foods that contain lactose.

Lactose is a sugar found in milk and foods made with milk (dairy products). Lactose is commonly added to beverages and foods such as cookies, cakes, bread, breakfast cereals, processed meats, soups, and sauces. It is sometimes used in flavorings and can be found in some prescription and over-the-counter medicines.

Lactose intolerance can cause discomfort.

People with lactose intolerance may feel sick or experience abdominal pain, cramps, bloating, stomach swelling, flatulence, diarrhea, or nausea after eating dairy or foods that contain lactose. The symptoms of lactose intolerance typically begin within 30 minutes to two hours after consuming lactose.

Lactose intolerance is not the same thing as a milk allergy, and people with a lactose intolerance do not always have to eliminate dairy.

What causes lactose intolerance?

Lactose intolerance is caused by lactose malabsorption — a digestive disorder in which your body can’t breakdown lactose. An estimated 68% of the global population has lactose malabsorption. Not everyone with lactose malabsorption has lactose intolerance, however.

A lactase deficiency is often responsible for lactose malabsorption and lactose intolerance. Lactase is an enzyme produced in your small intestine. This enzyme is essential for properly digesting dairy and breaking down lactose, turning milk sugar into two simple sugars (glucose and galactose).

People with a lactase deficiency do not have enough of the enzyme to break down lactose, and the sugar enters the colon rather than getting absorbed into the bloodstream; this is what causes the symptoms of lactose intolerance.

There are three main types of lactose intolerance:

  • Primary lactose intolerance. Your small intestine produces less lactase after infancy, and lactase production decreases as you get older. Eventually, you do not produce enough lactase properly to digest lactose.
  • Secondary lactose intolerance. Lactase production decreases after an illness, injury, or a surgery involving the small intestine. Bacterial infections, celiac disease, Crohn’s disease, radiation therapy for cancer in the abdomen can lead to lactose intolerance.
  • Congenital lactose intolerance. In rare cases, babies are born with a disorder that prevents the production of lactase.

When should you see the doctor for lactose intolerance?

Symptoms of lactose intolerance may develop in childhood, during adolescence, or even later in adulthood. 

Many people with low lactase levels are able to digest dairy and milk products without any symptoms of lactose intolerance. Some who experience symptoms of lactose intolerance may be able to eat small amounts of dairy without symptoms.

One meta-analysis found that almost all people with lactose intolerance could tolerate 12g of lactose in one intake, and up to 18g of lactose over the course of the day.

Talk to your primary care physician if you experience symptoms of lactose intolerance. Your doctor can determine if your health issues are related to lactose intolerance or some other health condition.