A2 Protein Explained

A cup of cow’s milk provides around 8g of protein and contains 9 of the essential amino acids (or the basic building blocks for protein formation) required by humans.

There are two main categories of milk proteins – casein and whey.  They differ both in their chemical composition and their physical appearance.  In cow’s milk approximately 80% of milk protein is casein and the remaining 20% is whey, whereas human milk is 40% casein and 60% whey.

The casein family of protein consists of several types of caseins including alpha-s1, alpha-s2 and beta casein. Each has its own amino acid composition, genetic variations, and functional properties [1].  The whey protein (also referred to as the serum protein) consists of approximately 50% ß-lactoglobulin, 20% α-lactalbumin, blood serum albumin, immunoglobulins, lactoferrin, transferrin, and many minor proteins and enzymes.  It is the beta casein protein component in cow’s milk that has attracted the attention of the science world with much research undertaken into the effect that digestion of the protein has on the human gut. Beta casein makes up about 30% of the total protein contained in cow’s milk and may be present as either the A1 or A2 major genetic type [2].

Most dairy milk produced commercially in Australia and internationally contains a mixture of A1 and A2 beta casein proteins however there are companies such as Beta A2 Australia which produce milk products that contain only the A2 beta casein.

Digestion of the A1 or A2 beta casein chains into smaller peptides and amino acids is where the major difference between the two proteins lies. During digestion of the A1 beta casein, a peptide known as Beta Casomorphin-7 (BCM-7) is produced[2]; this appears to be absent during digestion of the A2 beta casein protein. It’s the opioid like affect that this peptide has on the human gut that is driving health care professionals to investigate the difference in tolerance between different milks.

There are many scientific studies and research assessing the presence of the BCM peptide and subsequent gastrointestinal effects reported in some people. Some of the reported effects include delayed transit time through the bowel, affecting stool consistency [3], inflammation, and digestive discomfort including bloating, abdominal pain and flatulence [2]. Other symptoms reported in a recent study were those usually associated with lactose intolerance including increased gastrointestinal inflammation and worsening of post dairy digestive discomfort [4].

Consuming standard cow’s milk with a combination of A1 and A2 beta casein proteins will not necessarily affect everyone, however those presenting with unresolved gastrointestinal distress such as bloating, flatulence and poor emptying of the bowels may benefit from trialing a milk that is free of the A1 protein.

It’s important to remember, the benefits of A2 only protein milk are not just for those with gastrointestinal symptoms, it may simply ease the intestinal load and therefore equally benefit even those with healthy digestive systems.

Beta A2 Australia is a privately owned and operated Australian company based in Victoria. They produce a premium nutrition range ‘Beta A2’, based on home grown Australian A2 protein milk, that is naturally free of A1 beta casein.

What’s an easy way to describe the difference between regular milk and A2 milk?

Most people know that Whey Protein is an extract from milk, another type of naturally occurring protein in milk is Casein Protein.  There are a number of types of Casein Protein, two of which are A1 & A2 Beta Casein Protein.

Most cow’s milk contains both A1 & A2 Beta Casein Protein.  Beta A2 use milk from cows which naturally produce milk that does not contain the A1 Beta Casein Protein.   Hence the name A2 protein milk.

How do you remove the A1 protein from the milk? 

There is no need to remove A1 Beta Casein Protein.  The milk we use naturally does not have the A1 beta casein.

Just like humans have different blood types based on their genetics, cows can naturally product milk containing either A1 & A2 milk, OR A2 ONLY milk, it’s just a matter of genetics. 

Farmers may have a full A2 ONLY producing herd, or they may segregate the milk from the A2 ONLY cows that are naturally in their herds.

How are the cows selected?

The selection of cows is based on genetic testing. 

We test our milk for the absence of A1 protein once it is received.

Does A2 protein milk taste different?

A2 protein milk does not taste different.  It is delicious natural dairy milk.


[1] http://www.milkfacts.info/Milk%20Composition/Protein.htm

[2] Systematic Review of the Gastrointestinal Effects of A1 Compared with A2 β-Casein. Adv. Nutr. 2017 Sep; 8(5): 739–748.

[3] Milk Intolerance, Beta-Casein and Lactose. Nutrients 2015 Sep; 7(9): 7285–7297.

[4] Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behaviour of people with self-reported intolerance to traditional cows’ milk. Nutrition Journal volume 15, Article number: 35. 2015


Special Thanks to Dietitian Kate DiPrima for her contributions to this article.

A cup of cow’s milk provides around 8g of protein and contains 9 of the essential amino acids (or the basic building blocks for protein formation) required by humans.

There are two main categories of milk proteins – casein and whey.  They differ both in their chemical composition and their physical appearance.  In cow’s milk approximately 80% of milk protein is casein and the remaining 20% is whey, whereas human milk is 40% casein and 60% whey.

The casein family of protein consists of several types of caseins including alpha-s1, alpha-s2 and beta casein. Each has its own amino acid composition, genetic variations, and functional properties [1].  The whey protein (also referred to as the serum protein) consists of approximately 50% ß-lactoglobulin, 20% α-lactalbumin, blood serum albumin, immunoglobulins, lactoferrin, transferrin, and many minor proteins and enzymes.  It is the beta casein protein component in cow’s milk that has attracted the attention of the science world with much research undertaken into the effect that digestion of the protein has on the human gut. Beta casein makes up about 30% of the total protein contained in cow’s milk and may be present as either the A1 or A2 major genetic type [2].

Most dairy milk produced commercially in Australia and internationally contains a mixture of A1 and A2 beta casein proteins however there are companies such as Beta A2 Australia which produce milk products that contain only the A2 beta casein.

Digestion of the A1 or A2 beta casein chains into smaller peptides and amino acids is where the major difference between the two proteins lies. During digestion of the A1 beta casein, a peptide known as Beta Casomorphin-7 (BCM-7) is produced[2]; this appears to be absent during digestion of the A2 beta casein protein. It’s the opioid like affect that this peptide has on the human gut that is driving health care professionals to investigate the difference in tolerance between different milks.

There are many scientific studies and research assessing the presence of the BCM peptide and subsequent gastrointestinal effects reported in some people. Some of the reported effects include delayed transit time through the bowel, affecting stool consistency [3], inflammation, and digestive discomfort including bloating, abdominal pain and flatulence [2]. Other symptoms reported in a recent study were those usually associated with lactose intolerance including increased gastrointestinal inflammation and worsening of post dairy digestive discomfort [4].

Consuming standard cow’s milk with a combination of A1 and A2 beta casein proteins will not necessarily affect everyone, however those presenting with unresolved gastrointestinal distress such as bloating, flatulence and poor emptying of the bowels may benefit from trialing a milk that is free of the A1 protein.

It’s important to remember, the benefits of A2 only protein milk are not just for those with gastrointestinal symptoms, it may simply ease the intestinal load and therefore equally benefit even those with healthy digestive systems.

Beta A2 Australia is a privately owned and operated Australian company based in Victoria. They produce a premium nutrition range ‘Farmers Beta A2’, based on home grown Australian A2 protein milk, that is naturally free of A1 beta casein.


What’s an easy way to describe the difference between regular milk and A2 milk?

Most people know that Whey Protein is an extract from milk, another type of naturally occurring protein in milk is Casein Protein.  There are a number of types of Casein Protein, two of which are A1 & A2 Beta Casein Protein.

Most cow’s milk contains both A1 & A2 Beta Casein Protein.  Farmers Beta A2 use milk from cows which naturally produce milk that does not contain the A1 Beta Casein Protein.   Hence the name A2 protein milk.

How do you remove the A1 protein from the milk? 

There is no need to remove A1 Beta Casein Protein.  The milk we use naturally does not have the A1 beta casein.

Just like humans have different blood types based on their genetics, cows can naturally product milk containing either A1 & A2 milk, OR A2 ONLY milk, it’s just a matter of genetics. 

Farmers may have a full A2 ONLY producing herd, or they may segregate the milk from the A2 ONLY cows that are naturally in their herds.

How are the cows selected?

The selection of cows is based on genetic testing. 

We test our milk for the absence of A1 protein once it is received.

Does A2 protein milk taste different?

A2 protein milk does not taste different.  It is delicious natural dairy milk.


[1] http://www.milkfacts.info/Milk%20Composition/Protein.htm

[2] Systematic Review of the Gastrointestinal Effects of A1 Compared with A2 β-Casein. Adv. Nutr. 2017 Sep; 8(5): 739–748.

[3] Milk Intolerance, Beta-Casein and Lactose. Nutrients 2015 Sep; 7(9): 7285–7297.

[4] Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behaviour of people with self-reported intolerance to traditional cows’ milk. Nutrition Journal volume 15, Article number: 35. 2015


Special Thanks to Dietitian Kate DiPrima for her contributions to this article.

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