Usually when people experience tummy troubles from dairy, they rule it down to lactose intolerance. However, it could really be a milk protein intolerance. If consuming dairy seems to be contributing to digestive issues, it is important to determine what component of dairy is causing the issue. Many people find that they can tolerate some yoghurts or cheeses, while other brands or types don’t go down so well.

Cow’s milk is composed of 2 main proteins; casein and whey. Casein makes up 80% of the total protein content in milk. There are different types of casein, with beta-casein being the second most prevalent type.

Beta-casein comes in two different forms:

  • A1 beta-casein:

This form is generally higher in the milk from cows that originated in northern Europe.

  • A2 beta-casein:

This form is mainly found in breeds of cows that originate from Asia, Africa and part of Southern Europe.

Both A1 and A2 beta-casein proteins are found in regular milk. Whereas A2 Milk products are made from cows that only produce the A2 beta-casein protein, therefore A2 milk contains only A2 beta-casein.


The difference between A1 and A2:

A1 and A2 beta casein proteins are almost identical, they both contain 209 amino acids which are the building blocks that make up proteins. The only difference between them is in one of amino acids. This one different amino acid between A1 and A2 changes the way they are digested.

Digestion of A1 compared to A2:

The difference in the one amino acid between A1 and A2 beta casein, means when the A1 protein is broken down, it can create a peptide (shorter chain of amino acids) called beta-casomorphin-7 (BCM-7). This BCM-7 peptide is the reason why regular milk has been associated with more digestive issues compared to A2 milk.

Some studies have shown that people who drank cow’s milk with A1 beta casein had significantly softer stools, more bloating and abdominal pain compared to people who drank A2 milk. Research is still preliminary, however if you are experiencing digestive discomfort when consuming regular diary, A2 milk could be worth trying.


Does all dairy contain A1 beta-casein if it is not made from A2 milk?

There are limited A2-milk yoghurts and cheeses available commercially to purchase in Australia. Low protein dairy-based products such as butter are unlikely to contain high amounts of A1 beta casein that would trigger a reaction. Hard cheeses have very little lactose content, which is why many people with lactose intolerance can tolerate them even though they may experience symptoms from regular milk. However, as cheese is still high in protein, unless it is made primarily from A2 milk, it likely still contains A1 beta-casein protein. Fermented dairy foods such as yoghurt and kefir have additional bacterial cultures added. The bacterial cultures in fermented products can produce enzymes which may make these products easier to digest. If you are unsure whether you tolerate these products, you could test you individual tolerance starting with a small amount (half a usual serve) while maintaining a background diet of food you tolerate well. Monitor symptoms and increase you dose as tolerated.

Cow’s milk allergy

It is important to differentiate cow’s milk (dairy) allergy to an intolerance. Cow’s milk allergies are common in babies and infants. Most children outgrow a cow’s milk allergy by the age of three to five years, although in some people may not outgrow it.

A rapid onset of allergic symptoms after consuming cow’s milk may indicate a mild-severe allergic reaction. The timing of a rapid reaction may range from 15 minutes up to 2 hours. Symptoms may involve hives, swelling of lips, face or eyes, stomach pain, vomiting, diarrhoea and, in the case of a severe reaction, wheezing, noising breathing, tongue or throat swelling, hoarse voice, loss of consciousness and floppiness in children and babies. A severe allergic reaction to cow’s milk can be life threatening reactions (anaphylaxis) and should be treated as a medical emergency. Allergy tests (skin prick tests or IgE blood tests) are used to test for allergies and are usually positive or rapid onset symptoms.

Cow’s milk allergies can also present as delayed reactions, occurring two or more hours after consuming cow’s milk. Symptoms may include eczema, delayed vomiting and/or diarrhoea. Allergy tests are usually negative for these reactions. Diagnosis should only be made in consultation with a specialise paediatrician (for children) or an immunology or allergen specialist. An expert dietitian can assist to lead an elimination diet followed by a specific reintroduction challenge protocol to assess tolerance and provide advice to ensure the diet is nutritionally adequate.

What about lactose?

Lactose is a sugar (carbohydrate, not a protein) that is found naturally in animal milk products (dairy/cow, goat, sheep, buffalo and human breast milk). Lactose is a disaccharide and falls under the ‘D’ in FODMAP. Disaccharides contains two sugars molecules joined together and in the case of lactose these are glucose + galactose.

In order for lactose to be fully digested, the two sugars have to be separated by an enzyme called lactase, which is produced in lining of the small intestine. If there is not enough lactase enzyme to break down the lactose, it cannot be digested properly and can cause uncomfortable gut symptoms including diarrhoea, bloating, excess wind and tummy pain.

About 65% of the population has a reduced ability to produce lactase. When gut symptoms occur due to lactose not being digested properly, this is referred to as lactose intolerance. Lactose intolerance is less common in population’s who have had diary included as a dietary staple for generations, such as people of North European descent.  However, in communities of East Asian, African and Caribbean populations, lactose intolerance rates can be as high as 90%.

Having lactose intolerance does not mean you have to avoid dairy altogether. The amount of lactose that can be digested varies from person to person and most people with lactose intolerance can tolerate 4-7g lactose before they experience symptoms. To put that into perspective, there is about 12g lactose in a full cup of milk and only about 0.1g lactose in 50g of cheddar cheese.

Does A2 milk contain lactose?

Yes, A2 milk contains the same amount of lactose that is found in conventional cow’s milk.


How do you know if you have an intolerance?

If you are struggling to digest and tolerate cow’s milk, it’s important to get expert support to find out what is going on, rather than cutting this entire food group. Dairy is a great source of calcium, protein and many other vitamins and minerals, therefore cutting out dairy may increase your risk of nutritional deficiencies if you are not replacing dairy foods with suitable alternatives.

Our dietitian, Rebecca can help you navigate and manage food intolerances, including reactions to dairy. You can book an appointment with Rebecca online here.

Cow’s Milk Protein Intolerance
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