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Facts and advice about lactose intolerance and symptoms in kids, written by a pediatrician. Children are not lactose intolerant at birth. But at about elementary school age, a child can develop lactose intolerance. They may experience diarrhea and a stomach ache after drinking milk.
Lactose is milk-sugar
Lactose is a sugar found in milk. The lactose molecule is made up of two sugar molecules that are chemically joined together. In order for the intestine to absorb the sugar into the blood, an enzyme called lactase (NB: different from lactOse) must divide the sugar molecule in two.
Milk also contains milk proteins. Cow’s milk protein allergy is a fairly common disease in young children that should not be confused with lactose intolerance.
Read more about milk protein allergies here
Lactase is found in the intestinal lining
The small intestine is where the mucous membrane absorbs nutrients. The small intestine has finger-like and, on top of that, ‘fuzzy’ structures to increase its surface area and therefore maximize the absorption of nutrients. At the far end of the intestinal lining, on these fuzzy structures, is the lactase enzyme.
Celiac disease, or gluten intolerance, is a disease that destroys the intestinal lining. An untreated gluten intolerance therefore leads to lactose intolerance. Therefore, it is important to test children for gluten intolerance if they develop symptoms of lactose intolerance. The younger they are, the more important it is to detect.
Lactose intolerance symptoms in children
When lactose is not broken down in the small intestine by lactase, it is transported to the large intestine. The bacteria in the large intestine have enzymes that can break down lactose in slightly different ways. As residual products, the bacteria form gases, both foul-smelling and odorless. In addition, lactose retains fluid in the stool, and poop becomes loose i.e. diarrhea. The symptoms of lactose intolerance are thus gas formation, diarrhea and often stomach pain that occurs some time after a meal if it contained lactose.
Babies are not lactose intolerant
Read about gluten intolerance and celiac in children
It is extremely unusual for a baby not to have lactase. In total, forty babies with this condition are described in a scientific literature. Babies who do not have lactase get severe diarrhea as soon as they start consuming breast milk or formula. With the exception of these very few babies, all babies have lactase and are lactose tolerant until two years of age.
Lactose intolerance is normal
About two-thirds of the world’s population stop producing lactase during childhood. Therefore, lactose intolerance in older children and adults is normal. This usually happens after the age of seven, but it differs between different ethnic groups. The production of lactase decreases slowly, which means that if you have sudden stomach problems, then it’s usually not due to lactose intolerance.
In Scandinavia, we have a “genetic anomaly”. That means that most of us who have Scandinavian origins many generations back in time, continue to produce lactase and can eat unlimited amounts of lactose throughout life.
Blood tests for lactose intolerance
Blood tests that are available to detect lactose intolerance are genetic tests. It shows whether you possess the gene variant that control the production of lactase. If the gene is present, you are less likely to be lactose intolerant as an adult, and it is absent your lactase production will decrease slowly. So they do not say whether you can tolerate lactose or not. To know whether you are tolerant to lactose, you have to try it yourself. If you get typical symptoms of lactose intolerance and get rid of them with a lactose-free diet, you are probably lactose intolerant.
Lactose intolerance is not dangerous
Lactose does not harm the intestines or the body of those who are lactose intolerant. The symptoms are just unpleasant, not dangerous. Often people with lactose intolerance can eat a certain amount of lactose without symptoms, and this is what you should do. Avoid problems.
Lactose-free dairy products
In lactose-free dairy products, lactase is added. The lactase enzyme breaks down the milk sugar in the milk package before consumption. They are more expensive than ordinary dairy products and have no advantage whatsoever for anyone who can produce lactase. Additionally it’s not in any way dangerous to your health even if you produce your own lactase.
There are also tablets with lactase (Lactrase) available at the pharmacy. You can take these tablets when you want to eat more dairy products than you usually manage, without getting symptoms.
Foods that do not contain dairy products also do not contain lactose.
Read more:
Milk protein allergies in babies and milk-free alternatives for infants
Read about gluten intolerance and celiac in children
Baby poo – what is normal? Green poo or slimy – what does that mean?
Stomach pain in children – is it the appendix?
Gastroenteritis or winter vomiting in children – infection and incubation period