Lactose intolerance in children

Posted on 31 August 2017

We speak to a dietician and paediatrician to find out more about lactose intolerance in children and whether it is advisable to cut their dairy intake.

What is lactose intolerance?

‘Milk and milk products contain high concentrations of the disaccharide or ‘double sugar’ called lactose. Intestinal absorption of lactose requires that the sugar is broken down into a simple sugar by the enzyme lactase,’ says Irene Labuschagne a dietician at the Nutrition Information Centre at Stellenbosch University.

‘Lactose malabsorption is a common type of carbohydrate malabsorption caused by low lactase levels. When lactose malabsorption causes symptoms and discomfort, the result is called lactose intolerance, a syndrome,’ she explains.

Difference between lactose intolerance and a cow’s milk allergy

People sometimes confuse cow’s milk allergy (CMA) and lactose intolerance. A food allergy occurs when there is an abnormal and acute reaction of the immune system to one or more proteins present in food (such as casein, a protein found in milk). This type of reaction results in the formation of antibodies, which can trigger immediate symptoms, such as breathing difficulties, hives or swollen lips.

Food intolerance such as lactose intolerance is different from a food allergy because it doesn’t involve the immune system. It occurs when a person has an enzyme deficiency in the intestines. It causes moderate to severe gastrointestinal discomfort.

How common is it in children?

‘Research on lactose intolerance in children is very limited for the South African population, explains Irene. She adds that it tends to be more common in African and Asian population groups and has the lowest prevalence among children and adults of European descent.

Dr Ashley Wewege, a paediatrician at Mediclinic Constantiaberg adds that in his experience lactose intolerance is over self-diagnosed. Many people then go off dairy products and replace them with potentially less healthy alternatives such as soya and rice milk. Correlations have been found between suspected lactose intolerance and osteoporosis (linked to a low dietary intake of calcium), if patients lower their dairy intake too much.

Fortunately, even individuals with lactose intolerance can often tolerate up to 12-15 g of lactose, although symptoms become more prominent at doses above 12g, and substantial after 24g of lactose.


‘Ingesting smaller portions over the course of the day may minimise potential problems with larger acute lactose loads,’ explains Irene. Lactose tolerance also seems to improve if small amounts of lactose-containing foods are consumed with meals.

She advises patients to opt for better-tolerated or cultured dairy products such as cheese and yoghurt rather than milk.


If you suspect your child suffers from lactose intolerance because of stomach cramps and bloating, and the symptoms don’t improve with the above dietary guidelines, you should visit their doctor. They may be referred to a dietician to offer a tailored and healthy eating plan.

Some common tests include:

A lactose breath test: The sufferer breathes air into a few bags. It is tested for the presence of hydrogen, a gas produced when undigested lactose in the colon is fermented by bacteria.

A symptom questionnaire (often used together with a breath test). Symptoms may include: bloating, cramps, gas, vomiting and diarrhoea.

The lactose tolerance test (LTT): The patient consumes 50 g of lactose dissolved in water. Samples of capillary blood are taken to test the plasma glucose concentration.

Are there different causes?

There are four forms of lactose deficiency, which can lead to lactose intolerance:

Primary lactase deficiency is genetic. It affects older children and adults and is caused by the absence of a lactase persistence gene (the ability to keep producing lactase into adulthood). This explains why the prevalence of lactose intolerance tends to increase with age.

Temporary lactase deficiency related to premature birth. Dr Wewege adds that premature infants often don’t produce lactase in the beginning and may temporarily experience lactose intolerance. The problem often clears up on its own as the baby gains weight.

Secondary or acquired lactase deficiency is caused by an injury to the small intestine, usually in infancy, from acute gastroenteritis or other environmental causes. This is sometimes temporary and lasts while a patient recovers from a viral infection.

Congenital lactase deficiency is a rare recessive genetic disorder that prevents lactase expression from birth.


In the interest of our patients, in accordance with SA law and our commitment to expertise, Mediclinic cannot subscribe to the practice of online diagnosis. Please consult a medical professional for specific medical advice. If you have any major concerns, please see your doctor for an assessment. If you have any cause for concern, your GP will be able to direct you to the appropriate specialists.

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