Lactose Intolerance

Introduction to Lactose Intolerance

Your baby’s digestive system develops rapidly over their first few weeks. It’s no surprise that wind, hiccups, and poo can take up most of your day. As a new parent, it can be hard to work out what’s normal and what’s not. Although it’s relatively uncommon, some babies are lactose intolerant. In this article, we will look at what lactose intolerance is, the different types of lactose intolerance in babies, the signs of lactose intolerance, diagnosis, how to care for your baby with lactose intolerance and when to seek help.

What is baby lactose intolerance?

Some babies find it hard to digest the natural sugar (lactose) found in breastmilk and formula¹. This is called lactose intolerance. The main source of lactose in your baby’s diet will come from breast milk and/or infant formula.

What causes baby lactose intolerance?

Baby lactose intolerance is usually caused when your baby doesn’t have or doesn’t make enough of a digestive enzyme called ‘lactase’¹. Lactase is produced in the gut, and it helps to breakdown (digest) lactose in the diet¹.

The good news is baby lactose intolerance is relatively uncommon¹. Temporary lactose intolerance in babies can sometimes occur after a tummy bug or a long course of antibiotics². But it usually resolves in time on its own, but a lactose free diet will still be needed during this temporary period.

What are the different types of lactose intolerance?

There are different types of baby lactose intolerance:

Primary lactose intolerance:

This means your baby has low levels of the digestive enzyme lactase³. It’s rarely seen in children younger than three³. Primary lactose intolerance is sometimes seen in certain ethnic groups (e.g., people of Asian or African-Caribbean descent)³.

Secondary lactose intolerance:

This means your baby isn’t producing enough lactase due to damage to the cells in their gut. It’s usually temporary and caused by a stomach virus such as norovirus³. It tends to improve once the lining of the gut heals⁴.

Congenital lactose intolerance:

This means your baby doesn’t produce any lactase from birth, however it’s very rare³. Symptoms develop as soon as your baby is given breastmilk or infant formula⁴.

Developmental lactose intolerance:

If your baby was premature (born earlier than 34 weeks' gestation), their gut lining may be under-developed³. This could mean that they’re not able to produce enough lactase³. It usually disappears as your baby gets older and their digestive system matures³.

What are the common lactose intolerance baby symptoms?

Symptoms of lactose intolerance in babies often overlap with other conditions such as cow’s milk protein allergy, meaning it’s sometimes hard to differentiate. Symptoms tend to occur within a few hours of feeding¹. Here are some common signs of lactose intolerance in babies:

• Diarrhoea (loose, watery poo)³

• More wind than usual³

• Tummy pain, discomfort, or bloating³

• Stomach gurgling³

• Your baby isn’t gaining weight, although this is unusual unless your baby has the rare congenital form of lactose intolerance⁴

If you think your baby has lactose intolerance, it’s important to visit your GP who can help with a diagnosis.

How is lactose intolerance diagnosed?

When lactose intolerance is suspected, you may be advised to look out for symptoms after your baby eats lactose¹. Your GP may ask you questions such as ‘what are the symptoms? How severe are they? When do they start and how long for?’ It can be helpful to keep a diary of symptoms to bring to the appointment with you.

Your GP might ask you to take a sample of your baby’s poo (known as a reducing sugar test). This can help to detect if your baby isn’t absorbing lactose. However, the test isn’t recommended in children older than 2 years of age due to a high rate of false-negative results^1,3.

If your GP thinks your baby has lactose intolerance and you’re using infant formula, they may ask you to trial a lactose-free infant formula^2,5.

Food for lactose intolerance in babies

If you’re breastfeeding, continue to offer regular feeds as this will help to heal their gut⁵. Despite what you may have heard, you don’t need to follow a lactose-free diet as research has shown that this doesn’t change the amount of lactose in your breastmilk⁵. Although you may wish to try giving your baby lactase enzyme drops, which can be bought from a pharmacy^2,5.

If your baby is formula-fed, you may wish to try a lactose-free formula, but only do so on the advice of a healthcare professional, such as your GP, health visitor or public health nurse. Try to reintroduce your baby’s usual formula within eight weeks, once your baby’s gut has healed^1,4.

If your baby has started solids, avoid offering foods containing lactose (e.g. cow’s milk, yoghurt, cheese) to allow their gut to heal^3,4. But make sure you reintroduce these foods back into your baby’s diet once their symptoms have improved, as they contain calcium, which is an important nutrient for helping build strong bones and teeth². Most babies with lactose intolerance will be able to tolerate a certain amount of lactose, it might just take some experimenting to find out how much².

If your baby’s symptoms don’t get better or you’re worried that your baby may have primary lactose intolerance, visit your GP for further assessment. Your GP may refer you to a dietitian for nutritional advice.

What’s the difference between cows’ milk protein allergy and lactose intolerance?

Lactose intolerance and cow’s milk protein allergy (CMPA) are not the same thing. CMPA is a common food allergy that affects babies and infants⁷. It’s caused by an immune reaction to the protein found in cow’s milk⁷. It usually causes immediate or delayed allergic symptoms such as skin rashes, diarrhoea, and vomiting⁷.

Lactose intolerance doesn’t involve the immune system and therefore it isn’t a food allergy. The symptoms of CMPA and lactose intolerance can overlap, so it’s recommended that you speak to your GP so they can help with the right diagnosis⁴. For more information on CMPA, read our article.

Will my baby grow out of lactose intolerance?

Your baby’s lactose intolerance may resolve on its own, or they may be able to tolerate more lactose in their diet as they get older¹. However, for some people, lactose intolerance may be a long-term condition².

Your GP or paediatric dietitian may encourage you to reintroduce lactose-containing foods into your little one’s diet after a certain amount of time to see if there’s been a change in tolerance^1,6.

When to call your doctor, health visitor or public health nurse

You know your baby better than anyone else. The symptoms of lactose intolerance can be mild and often resolve with time. If you’re worried about your baby or notice any changes in their symptoms, it’s important that you seek advice from your health visitor, GP, or public health nurse.

How to take care of you

Looking after a baby with lactose intolerance is bound to affect your own emotional state. Remember that you’re not alone and it’s important to look after yourself. Try to ask friends and family for help and find time to do something for yourself such as having a bath, going for a walk or at the very least enjoying a hot cup of tea. If you or your partner feel out of control, anxious, depressed, or unable to cope, it’s important to speak to a doctor. Feeling this way isn’t unusual and it’s not something to be afraid to talk about.