Lactose Intolerance

Lactose Intolerance

Lactose intolerance has a specific cause. However, it has symptoms that are similar to other gastrointestinal conditions, like celiac disease or irritable bowel syndrome (IBS).

What Is Lactose Intolerance?

Lactose is a natural sugar found in milk and milk products. Lactose intolerance is a condition in which lactase enzymes, that help digest lactose, are either absent or deficient.

Without enough of this enzyme, lactose in foods or drinks is not well absorbed. This results in an excess of lactose in the gastrointestinal tract, as well as GI symptoms.

Lactose intolerance is very common. Worldwide, it is estimated that almost 70% of the population has some degree of lactose intolerance.

There are 3 types of lactose intolerance. They are primary, secondary, and congenital.

  • Primary (adult-type lactase deficiency). There is less and less lactase production over time. It is the most common type and it runs in families.

  • Secondary. Occurs following damage to the GI tract from other conditions.

  • Congenital. An infant may be born with lactose intolerance, but it’s very rare.

What Are The Symptoms of Lactose Intolerance?

Symptoms occur anywhere from 30 minutes to 2 hours after ingesting foods or beverages with lactose. A person may have nausea, belly (abdominal) bloating, abdominal cramps, gas, and diarrhea.

What Determines The Severity Of Symptoms?

Lactose intolerance severity varies from person to person - one person may ingest a small amount of lactose without symptoms, while another person may have very bothersome symptoms with the same amount of lactose. The severity of symptoms depends on several factors that include:

  • The amount of lactase produced by the small intestine

  • The amount of lactose in the diet

  • The presence of other ingredients in milk products or other foods in a meal


Lactose intolerance is usually diagnosed based on a person’s history of symptoms after ingesting lactose, as well as the reduction of symptoms when lactose-containing foods/drinks are omitted from the diet.

There are also two tests to diagnose lactose intolerance. There is a lactose tolerance test and a breath hydrogen test. Both involve measurements after ingesting a standard dose of lactose.


Central to the treatment of lactose intolerance is decreasing or eliminating lactose from the diet.

Lactase is available as a supplement, but its effectiveness is uncertain. And, it has to be taken 5 to 30 minutes before eating. Certain types of probiotics may also be part of treatment.

Lactose In The Diet

Common Sources of Lactose

  • Milk (skim, low-fat, whole) including buttermilk, powdered, evaporated, and sweetened condensed milk

  • Butter, half and half,  cream, light cream, whipping cream

  • Cheese (some types) such as ricotta, cream cheese, cottage cheese

  • Yogurt, sour cream

  • Ice cream, frozen yogurt, sherbet

  • Whey or whey protein (whey protein isolate is lactose-free)

Hidden Sources of Lactose

Lactose may be used as an additive, thus it may be hidden in prepared foods. Some examples include:

  • Bread and other baked goods

  • Breakfast cereals

  • Pancake, cookie, and biscuit mixes

  • Soups, instant potatoes

  • Breakfast drinks

  • Margarine

  • Luncheon or deli meats

  • Salad dressing

  • Candy, snacks

Calcium And Vitamin D

If you are lactose intolerant and you eliminate or lessen dairy products from your diet, you are also limiting your intake of calcium and vitamin D. These nutrients are important to many body functions.

Low levels increase the risk of osteopenia (weakened bones) and osteoporosis (bones that are very weak and brittle, with an increased risk for bone fractures).

To lessen the risk, you can increase non-dairy sources of calcium and vitamin D.

Non-Dairy Sources Of Calcium

  • Green vegetables such as broccoli, collard greens, arugula, spinach, bok choy, kale, okra

  • Fortified non-dairy milk products such as soy, coconut, almond milk

  • Seafood, such as canned salmon, sardines, clams, oysters, shrimp

  • Other foods such as tofu, almonds, cooked dried beans, sesame seeds, rhubarb

Non-Dairy Sources Of Vitamin D

Exposure to Sunlight

Vitamin D is sometimes called the sunshine vitamin because it is made when the skin is exposed to sunlight.


  • Non-dairy milk products such as soy, coconut, and almond milk fortified with vitamin D

  • Fatty fish - salmon, sardines, mackerel, herring, tuna

  • Other foods - liver, egg yolks, mushrooms

Living With Lactose Intolerance

Despite having intolerance to lactose, some people do eat lactose-containing foods. To help reduce symptoms, you might try the following:

  • Try small amounts of foods/drinks with lactose throughout the day, rather than large amounts at one time.

  • Combine foods that contain lactose with non-lactose foods.

  • You may better tolerate certain foods that contain lactose, like kefir and yogurt.

  • You may better tolerate some cheeses better than others. Examples of low-lactose cheeses are parmesan, Swiss, cheddar, hard mozzarella, brie, and feta.

  • Try lactose-free dairy products.

  • Try lactase enzyme tablets. Take them with you when you eat away from home.

For More Information

American Gastroenterological Association (2020). Lactose intolerance. Retrieved 12-3-2020 from

National Institute of Diabetes and Digestive and Kidney Diseases (2018). Lactose Intolerance. Retrieved 12-3-2020 from