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Written By Lucy Upton

Cow’s Milk Protein Allergy or Lactose Intolerance?

One of the biggest sources of confusion when it comes to reactions to milk is whether symptoms are a milk intolerance or milk allergy.  Understanding if your child is intolerant or allergic to cow’s milk can be a challenge, as both affect the consumption of dairy products and have some crossover with similar signs and symptoms. Understandably, there is plenty of confusion regarding the difference between Cow’s Milk Protein Allergy (CMPA) and lactose (or milk) intolerance.

However, it is important to distinguish between CMPA and lactose intolerance to ensure the right dietary management is put in place, especially for children with CMPA who will continue to react to lactose-free products.  The key to understanding a milk allergy vs a milk intolerance is recognising that a milk allergy is a reaction to the PROTEINS in cow’s milk, and intolerance is typically a reaction to the SUGAR (Lactose) in Cow’s Milk.

Keep on reading this blog to learn more about CMPA, lactose intolerance, and where they differ.

This blog will cover

  • What is Cow’s Milk Protein Allergy

  • Examples of Cow’s Milk Protein Allergy symptoms

  • What is Lactose Intolerance, and when can it occur

  • Examples of Lactose Intolerance Symptoms

  • Where to get more help with your child’s symptoms to milk

Cow’s Milk Protein Allergy

CMPA affects an estimated 2-3% of 1–3-year-olds in the UK (Allergy UK., 2017) however approximately 80% will outgrow their allergy by 3 years old (Venter et al., 2007).

CMPA is a reproducible immune-mediated allergic reaction to proteins found in cow’s milk. Essentially the immune system is getting it wrong and intreprets something safe (in this case proteins in cow’s milk) as a threat. There are different types of CMPA, which generally can be classified as immediate (IgE mediated) or delayed (Non-IgE mediated), according to their underlying immune mechanism. You can find out more about the different types of CMPA, and their symptoms in another blog, HERE.

Symptoms are diverse and depend on the type of allergy a child has but broadly they include gastrointestinal, skin, and respiratory symptoms. For example:

Immediate symptoms of cow’s milk proteins can include; hives, redness, vomiting, diarrhoea, facial/lip/ear swelling, running nose, wheezing, hoarse cough or cry

Delayed symptoms of cow’s milk proteins can include; eczema (often persisting despite treatment, or difficult to manage), constipation, diarrhoea, blood and/or excessive mucus in stools, reflux, colicky abdominal pain and faltering (dropping) growth

Much of the confusion about whether a child has a milk intolerance or milk allergy comes down to babies and children with delayed-type milk allergy.  As symptoms are often not the ‘typical’ symptoms people expect when you hear ‘food allergy’ 

Lactose Intolerance

On the other hand, lactose intolerance does not involve the immune system. Instead, it occurs because the digestive system is unable to fully digest lactose (the sugar in milk) as it has little or none of an enzyme called lactase (which breaks down lactose). Therefore, instead of digesting and absorbing lactose, it stays in the gut where it can be metabolised by gut bacteria and results in gastrointestinal symptoms, some of which are similar to CMPA.

Symptoms can include watery diarrhoea, bloating, discomfort while feeding, bulky frothy watery stools, pain on passing wind/ stools and/ or faltering growth. Where lactose intolerance symptoms most noticeably differ from CMPA is that it does not present with skin or respiratory symptoms, they are largely just digestive.

Lactose intolerance in babies and children is very rare. Lactose intolerance due to inherited primary lactase deficiency is uncommon before the ages of 2-3 years old and can become more common later in life, differing from CMPA. The most common type of lactose intolerance is known as ‘secondary’ or ‘transient’ lactose intolerance and occurs temporarily in children following a stomach bug or gastroenteritis. This is because the bug can clear some of the enzymes involved in breaking down lactose from a child's gut, meaning the body temporarily cannot digest lactose effectively, however, these cases usually resolve on their own in the short term e.g. weeks.

Very occasionally, a child with CMPA can also present with a temporary lactose intolerance. This is often when symptoms of CMPA have included digestive challenges such as persisting diarrhoea.

Management differences of CMPA vs Lactose Intolerance

 Children with Cow’s Milk Allergy and Lactose Intolerance need different dietary management. Some of the key differences are highlighted below:

MILK CHOICE

  • Milk and dairy choices for Children with Lactose Intolerance - Lactose-free formula and/or lactose-free milk, yoghurt and dairy options

  • Milk and dairy choices for CMPA children - Under 1 babies will need to have a specialised formula milk prescription from a health professional, or a breastfeeding mother may have to trial a milk-free diet. From 1 year of age (and from 6 months in food) children will need to have fortified plant-based milk alternatives e.g. based on soya, oat. They cannot have lactose-free options as lactose-free milk still contains milk proteins

LENGTH OF TIME MILK-FREE

  • Children with lactose intolerance - will often only have to be lactose-free for several weeks before reintroducing it to their diet. Management is short-term

  • Children with CMPA - will often have to be milk-free for at least 6 months before following a specialised milk reintroduction protocol aka The Milk Ladder. Children with immediate symptoms of CMPA are likely to have to exclude milk for years and a small % they may never outgrow their milk allergy. Management is therefore usually long-term (months to years)

 If you are unsure about your child’s symptoms and would like some support, please be in touch via the contact page and we would be happy to see you in our virtual clinic for some 1:1 specialised advice

This article aims to provide general advice. It does not provide personalised nutritional advice. If you have any questions or concerns, please always seek advice from a registered healthcare professional. 
Written with the support or Emilia Fish, Student Dietitian and RNUTR
Lucy Upton
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How to Manage Constipation During Weaning