Lactose intolerance: babies, kids & teens

What is lactose intolerance?

Lactose intolerance is when the body can’t break down lactose. This problem happens because there isn’t enough lactase in the stomach.

Lactose is a complex sugar. It’s present in all breastmilk, dairy milk and other dairy products. It makes up around 7% of breastmilk and infant formula.

Lactase is an enzyme. Enzymes break down food chemicals so the body can use them.

Lactose is important for your baby’s health and development. It provides around 40% of your baby’s energy needs and helps him absorb calcium and iron.

Causes of lactose intolerance

There are three main causes of lactose intolerance.

Lactase non-persistence (hypolactasia)
This happens when your child’s lactase enzymes gradually start to decrease. This is genetic and very common – about 70% of people have this type of lactose intolerance. Symptoms can start to happen after the age of five but are usually more noticeable in teenagers and young adults. Children can usually still tolerate small amounts of lactose in their daily diets.

Congenital lactase deficiency (alactasia)
This happens when babies are born with no lactase enzymes at all. This is genetic but extremely rare. Babies with this kind of lactose intolerance have severe diarrhoea from the first day of life. To thrive, they need a special diet from the time they’re born.

Secondary lactose intolerance
This can happen if a child’s digestive system is upset by infections like gastroenteritis, which alter the lining of the stomach and small intestine. This kind of lactose intolerance is short term and usually improves after a few weeks.

Conditions like coeliac disease can also cause secondary lactose intolerance. Once these conditions are being managed properly, lactose intolerance should be less of a problem.

Common symptoms of lactose intolerance

Symptoms of lactose intolerance in babies and children include:

Babies with lactose intolerance might also have symptoms like:

nappy rash
crankiness or irritability
trouble settling
attachment problems during breastfeeding
failure to gain weight.

Even if your baby has these symptoms, it doesn’t always mean she’s lactose intolerant. Some or all of these symptoms can be common in healthy breastfed infants.

If you think your baby or child has the symptoms of lactose intolerance, you should talk with your GP.

Sometimes lactose intolerance is confused with food allergies like cow’s milk allergy. Some common food allergy symptoms include vomiting, blood or mucus in diarrhoea, hives and swelling around the eyes – these aren’t symptoms of lactose intolerance. If your child has symptoms like these, you should see your GP for a proper assessment.

Diagnosing lactose intolerance

These are the two main ways to diagnose lactose intolerance:

Hydrogen breath test: this tests the amount of hydrogen gas in a child’s breath. Lactose-intolerant children have higher levels of hydrogen in their breath.
Elimination diet: this involves removing foods containing lactose from a child’s diet to see whether symptoms improve. If the symptoms come back once the foods with lactose are reintroduced, lactose intolerance is most likely the cause of the problem.

Because some of the symptoms of lactose intolerance and food allergy are similar, diagnosing lactose intolerance can sometimes be tricky.

Treatment: lactose intolerance in babies

The treatment for lactose intolerance in babies often depends on the cause. And no matter what’s causing your baby’s lactose intolerance, it’s important to soothe and comfort your baby when he’s showing symptoms.

Congenital lactase deficiency
If your baby has congenital lactase deficiency, your GP, paediatrician or dietitian will guide your child’s treatment.

Secondary lactose intolerance
For a breastfed baby with secondary lactose intolerance caused by gastroenteritis, you should be able to continue breastfeeding.

Weaning isn’t usually recommended because breastmilk has so many nutritional benefits and lactose is good for your baby’s growth. Your child can usually tolerate a small amount of lactose, and gradually increasing it can help her body produce more lactase.

If your baby is formula fed or you’re considering giving him formula, consult your GP or a dietitian before using or changing to a low-lactose or lactose-free infant formula. If your child is under six months, avoid using soy-based infant formula.

Talk to your GP if you’re thinking of using Lacteeze drops in expressed breastmilk or Lacteeze tablets. There’s some debate about the effectiveness of these treatments. Also talk to your GP if you want to try replacing breastmilk or alternating breastmilk with formula, or you’re generally worried about your baby’s nutrition.

Treatment and management: lactose intolerance in older children and teenagers

If your older or teenage child is diagnosed with lactose intolerance, you can reduce the amount of lactose in her diet. But you don’t need to get rid of products with lactose completely, especially if your child eats only small amounts of them with other foods during the day.

The following food and diet tips can help.

These foods are OK:

cheeses with very low lactose content – brie, camembert, cheddar, colby, edam, fetta, gouda, havarti, mozzarella, parmesan, halloumi, Swiss and Tilstat
yoghurt – the bacteria in yoghurt breaks down the lactose so it’s usually fine for your child to eat
calcium-fortified soy products – soy yoghurt, soy milk, soy ice-cream and soy cheese
lactose-free cow’s milk
butter and cream – these contain only small amounts of lactose and are usually fine to eat
bread, cereals, fruit, vegetables, meat and other protein foods
full-fat milk – the fat in full-fat milk gives your child’s body longer to digest lactose.

Watch out for these foods:

milk ice-cream and milk desserts
cream cheese, processed cheese and cheese spread
muesli bars
instant mashed potato and vegetables with added milk or white sauces.

Check the ingredients in these foods:

biscuits, cakes and cake mixes
soups
mayonnaise
milk chocolate.

Lactose overload in babies

Lactose overload isn’t the same as lactose intolerance – that is, it isn’t a problem with the production of lactase. Rather, lactose overload happens when a baby consumes large amounts of lactose at one time and can’t break it all down.

Lactose overload can happen when mothers have a natural oversupply of breastmilk in their baby’s early weeks.

It can also happen when breastfed babies:

have a pattern of short breastfeeds
feed frequently and switch breasts before the breasts have been emptied
drink more first milk than last milk. The lactose-rich first milk passes through the digestive system faster than the last milk, and there’s not enough time for all the lactose to be broken down

And it can happen when bottle-fed babies drink a lot of milk, but this isn’t common.

If your baby has symptoms of lactose overload, feed him in a position that ensures he gets all the milk from each breast. Also, feed from one breast only for a four-hour block before moving onto the other breast for the next four hours. If over-feeding is causing the overload, try not to feed more often than every three hours.