The inability to digest significant amounts of lactose, the major sugar found in milk and dairy products. 

Lactose Intolerance
Lactose intolerance is the inability to digest significant amounts of lactose, the major sugar found in milk and dairy products.

What causes lactose intolerance?
Lactose intolerance results from a shortage of the enzyme lactase. Lactase breaks down the lactose so that it can be absorbed into the blood stream. When there is not enough lactase to digest the amount of lactose consumed, symptoms of lactose intolerance can occur. Lactose intolerance is not dangerous, but can be uncomfortable.

What are the signs and symptoms of lactose intolerance?
Common symptoms include nausea, cramping, bloating, gas, and diarrhea. Symptoms may be mild to severe and usually begins about 30 minutes to 3 hours after eating or drinking foods containing lactose. The severity of symptoms depends on many factors, including the amount of lactose a person can tolerate and a person’s age, ethnicity, and digestion rate.

How is lactose intolerance diagnosed?
A hydrogen breath test is a common test used to diagnosed lactose intolerance which measures the absorption of lactose in the digestive system. This test measures the level of a gas called hydrogen in your breath. Hydrogen is produced by bacteria in the colon (large intestine) in response to undigested lactose. Hydrogen is carried through the blood stream to the lungs, where it is breathed (exhaled) out. High levels of hydrogen in your breath means that lactose is not being digested properly.

Treatment Options and Prevention
Lactose intolerance is relatively easy to manage with dietary changes. Many children and adults do not need to avoid lactose completely, because individuals differ in the amounts of lactose they can handle. The amount of lactase enzyme that the body produces cannot be increased, however there are over-the-counter lactase enzymes (i.e. Lactaid®) that can be taken to help control symptoms. 

To reduce symptoms of lactose intolerance:

  • Choose soy milk, rice milk or even try almond milk
  • Choose soy yogurt, coconut yogurt or rice yogurt
  • Choose low-lactose dairy products such as aged cheese, cream cheese or sherbet
  • Choose special dairy products such as Lactaid® milk, Lactaid® ice cream, Lactaid® cottage cheese, Lactaid® or milk
  • Use lactose containing tablets such as Lactaid® or Dairy Ease® with dairy products.

* Be aware of hidden or added sources of lactose in dry milk solids, non-fat dry milk-powder, whey, curds, and in milk by-products.

* Limit your quantity of dairy products; even people with lactose intolerance can usually tolerate small amounts of dairy products.

Lactose content of common dairy products:

  • Milk (250 ml, 1 cup) 13g
  • Evaporated Milk (15 ml, 1 Tbsp.) 1.5g
  • Sweetened Condensed Milk (250 ml, 1 cup) 26g
  • Acidophilus Skim Milk (250 ml, 1 cup) 11g
  • Yogurt (175 g, ¾ cup) 4g
  • Cottage Cheese (125 ml, ½ cup) 3g
  • Mozzarella or Cheddar Cheese (50g, 1 ½ oz.) <1g
  • Cream Cheese (50 g, 1 ½ oz.) 1.5g
  • Butter (5 ml, 1 tsp.) <1g (trace)
  • Ice Cream (125 ml, ½ cup) 3-6g
  • Sherbet (125 ml, ½ cup) 2g


It is important to obtain an adequate amount of calcium and vitamin D. Dairy products are a good source of calcium. Talk to your doctor about ways to get enough calcium if you avoid dairy products. Foods other than dairy products that contain calcium include:

  • Calcium-fortified drinks such as orange juice, soy milk and rice milk
  • Fish with edible bones such as canned salmon
  • Alfalfa or soy sprouts
  • Tofu soybeans, pinto beans, and navy beans
  • Green vegetables such as broccoli, kale, bok choy (Chinese cabbage) and turnip greens
  • Almonds
  • Sesame seeds
  • Molasses

When to Seek Medical Advice
If you have signs and symptoms of lactose intolerance, talk to your doctor. Don't diagnose yourself. Your symptoms could be an indication of another illness. Your doctor can help determine if you have lactose intolerance or another condition.

Additional Resources:

  1. American Gastroenterological Association
  2. American Dietetic Association
  3. Lactaid®