Milk: A1 too many proteins

I’m sure you’ve all heard about the rising popularity in A2 milk that’s apparently so much better for your health. A type of milk that contains only A2 protein, none of that A1 stuff.

Most of the brands of milk on our supermarket shelves have both A1 and A2 protein in them, while The a2 Milk Company’s milk has (you guessed it) A2 only.

What is all the hype about? Why is drinking A2 milk better? via Wikimedia Commons

So what on earth are proteins A1 and A2?

The dairy milk that is consumed by 68% of the Australian population contains an abundance of proteins and amino acids. More than 95% of which are constituted of caseins and whey proteins. Among these caseins, beta caseins A1 and A2 are the most common.

Beta caseins A1 and A2 are almost identical in that their polypeptide chain only differs by one amino acid, at the 67th position. This results in a conformational change in the secondary structure of the A1 protein, which causes it to fold differently to the A2 protein.

Difference in A1 and A2 beta casein polypeptide chains. Diagram adapted from Woodfork K (2007) Devil in Milk

When the A1 variant is digested, bioactive peptide beta casomorphin 7 (BCM 7) is generated. On the other hand, A2 beta casein releases minimal amounts of BCM7 under normal gut conditions.

How does BCM7 affect the body?

BCM7 is a mu-opioid ligand that causes gastrointestinal (GI) inflammation. Mu-opioid receptors are found widely through human physiology; and affects the mechanics of propulsion in the gastrointestinal tract.

Gut inflammation can cause malabsorption of fluids and nutrients in faeces. Coupled with delays in GI transit, you simultaneously end up with constipation and loose stools. Other GI symptoms include abdominal pain and bloating. These symptoms are commonly seen in those that are lactose-intolerant.

In a small human study involving 45 subjects, with 23 diagnosed as lactose-intolerant, the test subjects were given common commercial milk that contains both A1 and A2 proteins, and compared it to consuming milk containing only the A2 protein.

The results showed that A2 milk did not increase uncomfortable digestive symptoms, however, ordinary commercial milk showed an exacerbation of stomach unpleasantness.

This demonstrates that A2 is correlated with digestive wellbeing. For those who self-report an intolerance to milk, A2 milk may be a suitable selection to prevent stomach upsets.

How did A1 come about?

It’s good to note that all dairy yielding mammals produce A2-like beta casein proteins in their milk; including cows, humans, goats, and sheep. Meaning, originally, all cows produced A2 milk.

A few thousand years ago, a mutation occurred in some European dairy cow herds, which introduced the A1 variation. Cows in the European, Australian, and New Zealand regions exhibit the A1 protein. Still, native cows across Asia and India only have the A2 allele.

Misunderstandings about the A1 protein

Several studies across the world are linking the consumption of milk containing A1 (A1 milk) with chronic diseases such as type 1 diabetes, increased risk of heart disease, sudden infant death syndrome (SIDS), autism, and digestive problems.

Nonetheless, the European Food Safety Authority (ESFA) found no relationship between A1 milk intake during childhood, and the development of these health problems. Insufficient evidence exists to make this claim.

All A1 does is make us have an upset tummy. SO, if you’re experiencing symptoms similar to that of lactose-intolerance, like abdominal discomfort or bloating, it may be because of the nasty little A1 proteins wreacking havoc your gut. If that’s the case, next time consider trying A2 milk.

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7 Responses to “Milk: A1 too many proteins”

  1. Yang says:

    I can always see the slogan in A2 milk which says” milk that only has a2 protein”. That’s eyes-catching but I’ve never know what it means. Now I have a better idea! Thanks for your explanation!

  2. Claudia says:

    Hi chiahsingh, thank you for pointing that out. I’m glad you enjoyed it. It’s hard to explain some concepts without using specific terminology, and trying not to be too long-winded; but I will see to adding a short explanation to some of the biological terms.

  3. Claudia says:

    Hi Ehlana, it is quite confusing to explain without knowing the underlying cause, isn’t it? As it turns out A2 milk just doesn’t produce stomach discomfort! Hope you have an easier time explaining the differences to customers now.

  4. Claudia says:

    Hi Siân, you’re welcome! I, too, was puzzled about whole fiasco regarding the different types of milk. And then I thought, why not research and write about it while I’m at it.

  5. chiahsingh says:

    It’s interesting to learn difference between A1 and A2 protein, thank you for the blog. Some jargon in the blog may be difficult to understand for some audiences. But generally it’s well-framed and questions are used to attract attention. Well done.

  6. Ehlana Tompsett says:

    THANK YOU! I work at a supermarket and am constantly trying to explain to customers the difference between the two proteins but have never managed to get the words right. This was such a good read, it explains it so well!

  7. Siân says:

    I have always wondered what the difference was between the milk protein types, thank you for your entertaining explanation!