Lactose Intolerance

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Lactose intolerance is a condition in which your body does not correctly digest a sugar found in milk products (lactose). The small intestine does not make enough of an enzyme (lactase) that helps the body absorb food. The lactose continues undigested into the large intestine where bacteria feed off of it and produce gas and acid causing symptoms of lactose intolerance.

There are three types of lactose intolerance:

  • Primary lactose intolerance – normal result of aging for some people.
  • Secondary lactose intolerance – result of illness of injury.
  • Congenital lactose intolerance – passed down from the family (genetic).

Lactose intolerance is more common in adults and is not dangerous. Approximately 30 million American adults have some amount of lactose intolerance by age 20. People who are Hispanic, Asian, or African American are more likely to develop lactose intolerance.


Babies are born with the ability to digest milk, including breast milk. Premature babies are more likely to have a lactase deficiency because their lactase levels do not increase until the third trimester of pregnancy. Some children, as they grow, produce less lactase and may see symptoms of lactose intolerance as early as age 3-6 years old. In other children, symptoms may not appear until they are in their teens or are adults.

Lactose intolerance can be confused with cow milk allergy. Milk allergy is a reaction by the body’s immune system to one or more milk proteins and can be serious when just a small amount of milk, or something made with milk,, is eaten. Milk allergy most often appears in a child during their first year of life, while lactose intolerance occurs more often in adulthood.

In younger children who become lactose intolerant, the cause may be an infection or allergic reaction that has caused a bit of damage to the small intestine. In other cases, lactose intolerance may be due to a diagnosis of Crohn’s Disease, Celiac disease, or a parasitic infection.


Symptoms often occur 30 minutes to 2 hours after drinking milk or eating something with milk in it and include:

  • Excess gas
  • Abdominal Bloating
  • Abdominal cramping
  • Diarrhea
  • Nausea


If the doctor suspects lactose intolerance, he/she may suggest avoiding all milk products for 2 weeks to see if symptoms go away. Small amounts of milk will be added in the diet each day to see if symptoms return. If avoiding milk products helps stop the symptoms, but the symptoms come back again after adding milk back in the diet, it may be a lactose intolerance problem.

There are also several tests that can help tell if a person has lactose intolerance:

  • Lactose Intolerance Breath Test – Two hours after drinking a liquid that contains lactose and water, blood tests are done to measure the amount of glucose in the bloodstream. If the glucose level doesn’t rise, it means the body isn’t properly digesting and absorbing the lactose-filled drink.
  • Stool acidity test – Used for infants and children who can’t do the other two tests. A stool sample is taken and tested to see if lactic acid and other acids are in the stool.
  • Endoscopy– passed through the mouth or nose and into the small intestine to get a small sample of the lining of the small intestine to measure lactase levels.


There is not a treatment to cure lactose intolerance. People with lactose intolerance usually find relief by reducing the amount of dairy products they eat and using special products made for people with this condition. Some children may be able to tolerate some lactose and will need to follow a low-lactose diet (very few milk products). Other children may need to follow a lactose free diet – a diet that does not allow ANY milk products.

Lactose-free milk and lactose-reduced milk and milk products are identical to regular milk except the lactase enzyme has been added. Lactose-free milk remains fresh for about the same length of time as regular milk and may have a slightly sweeter taste than regular milk. Over the counter enzyme drops or tablets can be also be added when using milk or milk products to make these foods more tolerable.

Many foods contain milk products so it is very important to read labels carefully when following a lactose free diet. Lactose free products are available at most grocery stores, including lactose free milk, cheese, and ice cream. If any of the following words are listed on the food label, the product contains lactose:

  • Milk
  • Lactose
  • Whey
  • Curds
  • Milk-by-products
  • Dry milk solids
  • Non-fat dry milk powder.

Lactose is also used in some prescription medicines and over-the-counter medicines like products to treat stomach acid and gas. These medicines most often cause symptoms in people with severe lactose intolerance.

It is important that your child receive an adequate amount of calcium, vitamin D, and riboflavin from other sources (such as vitamins or foods enriched with these nutrients). There are many nondairy foods that contain calcium, including:

  • Broccoli, okra, kale, collards, and turnip greens.
  • Canned sardines, tuna, and salmon.
  • Calcium-fortified juices and cereals.
  • Calcium-fortified soy products such as soy milk, rice milk, tofu, and soybeans.
  • Almonds.
  • Spinach
  • Pinto beans
  • Tuna
  • Yogurt with active and live cultures
  • oranges

*Consider meeting with one of our dieticians for a nutritional consult. Call (865) 546-3998 to schedule an appointment.