What’s the Difference Between A1 and A2 Milk

A1 and A2 milk are two varieties of milk classified based on the type of beta-casein present in the milk. Therefore, the main difference between A1 and A2 milk is that A1 milk contains A1 beta-casein whereas A2 milk contains A2 beta-casein. 

Furthermore, the digestion of A1 beta-casein produce beta-casomorphin-7 (BCM-7) during digestion, which can cause alterations in the gastrointestinal function and increase inflammation in the gut. However, A2 beta-casein does not produce BCM-7 during digestion.

Key Areas Covered

1. What is A1 Milk
     – Definition, Facts, Health Effects
2. What is A2 Milk
     – Definition, Facts, Health Effects
3. What are the Similarities Between A1 and A2 Milk
      – Outline of Common Features
4. What is the Difference Between A1 and A2 Milk
      – Comparison of Key Differences

Key Terms

A1 Beta-Casein, A1 Milk, A2 Beta-Casein, A2 Milk, Beta-casomorphin-7 (BCM-7), Digestive Health

What is A1 Milk

A1 milk is a variety of cow’s milk that only contains A1 beta-casein. Generally, the majority of the milk in the market contains A1 beta-casein. This means the cow breeds in Australia, the United States, and Northern Europe produce A1 milk. The 67^th amino acid in the beta-casein chain is histidine, which allows the formation of beta-casomorphin-7 (BCM-7) during digestion.

Figure 1: Bovine β-Casomorphin 7

BCM-7 is a 7 amino acids long, opioid peptide, associated with various disease conditions related to the digestive system including slowing down of the bowel movements from the stomach to anus, and inflammation in the gut. Apart from that, the absorption of BCM-7 to the bloodstream can cause schizophrenia, autism, and other neurological disorders. In addition, the consumption of A1 milk increases the risk of Type 1 diabetes among children. Moreover, regular consumption of A1 milk can cause coronary heart disease. Some researchers also claim that BCM-7 may cause Sudden infant death syndrome (SIDS) in infants.

What is A2 Milk

A2 milk is another variety of cow’s milk which only contains A2 beta-casein. It was first marketed by The a2 Milk Company. The 67^th amino acid of the A2 beta-casein is proline, which forms strong bonds, preventing the production of BCM-7 during digestion. 

Figure 2: A2 Milk

The milk produced by other mammals including humans, sheep, and goat is similar to the A2 milk by the presence of proline. Since A2 milk does not produce BCM-7, it does not develop unwanted health conditions upon consumption.

Similarities Between A1 and A2 Milk

• A1 and A2 milk are two types of milk classified based on the type of beta-casein present in milk.
• Beta-casein is one of the three types of casein found in milk. It consists of a chain of 209 amino acids. A1 beta-casein and A2 beta-casein are two genetic variants.
• Also, A1 and A2 milk contain different beta-casein structures.
• Besides, cow’s milk in Europe, America, Australia, and New Zealand contain both types of beta-caseins.

Difference Between A1 and A2 Milk

Definition

A1 milk refers to the cow’s milk that only contains A1 beta-casein while A2 milk refers to the cow’s milk that only contains A2 beta-casein. Hence, this is the fundamental difference between A1 and A2 milk.

Geographical Location

The cows that produce A1 milk mainly live in Australia, United States, and Northern Europe while the cows that produce A2 milk mainly live in the Channel Islands and Southern France.

Breeds

Moreover, the cow breeds including Holstein, Friesian, Ayrshire and British Shorthorn mainly produce A1 milk while the cow breeds including Guernsey, Jersey, Charolais, and Limousin mainly produce a2 milk.

Genetic Status

Also, A1 milk is a result of A1 gene mutation, which occurred hundreds of years ago from Holstein cow breed while older cow breeds produce A2 milk.

67^th Amino Acid

The 67^th amino acid in the A1 beta-casein is histidine while the 67^th amino acid in the A2 beta-casein is proline. This is another important difference between A1 and A2 milk.

Effect on the Milk Production

A1 mutation increases the milk production while A2 variety has no effect on increasing the milk production.

BCM7

Another major difference between A1 and A2 milk is that the digestion of A1 milk produces BCM7 while the digestion of A2 milk does not produce BCM7.

Health Effects

A1 milk causes alterations in the gastrointestinal function and increases the inflammation in the gut due to the presence of BCM7. However, A2 milk does not cause any mild to serious medical conditions.

Conclusion

A1 milk contains A1 beta-casein which produce BCM-7 during digestion; BCM-7 causes several health effects including digestive problems, Type 1 diabetes in children, SCID, and heart disease. On the other hand, A2 milk only contains A2 beta-casein, which does not produce BCM-7 during digestion. Therefore, it does not cause mild to severe health effects. The main difference between A1 and A2 milk is the type of beta-casein present in the milk and health effects.

Reference:

1. Sodhi, Monika et al. “Milk proteins and human health: A1/A2 milk hypothesis” Indian journal of endocrinology and metabolism vol. 16,5 (2012): 856. Available Here

Image Courtesy:

1. “Bovine β-casomorphin 7” By D Dinneen – Own work (Public Domain) via Commons Wikimedia  
2. “A2 brand milk” By BlackCab – Self-photographed (CC BY-SA 3.0) via Commons Wikimedia