A2 Milk: What's the Deal?

A2 Milk: What's the Deal?

Find out why people are claiming A2 milk to be a healthier substitute for regular cow's milk with significant health benefits.

Short read

You may have noticed a new type of milk on supermarket shelves, proudly distinguishing itself from neighbouring cartons. Its supporters claim it is easier on the gut, less inflammatory, better for the heart, and better for the brain.

It's A2 milk, but what does that mean?

The two primary proteins in milk are whey and casein. Whey is popularly isolated as a protein supplement and is generally the more agreeable of the two. It doesn't have nearly as much likelihood of causing or triggering allergic reactions. Casein, on the other hand, can be a bit more problematic. The majority of milk protein, about 80%, is the casein component. A subcomponent of casein is beta-casein. Beta-casein can further be broken down into A1 and A2 subtypes.

Beta-casein is a protein containing a sequence of 209 amino acids. In A1 beta-casein, the 67th amino acid in the sequence is histidine. In A2 beta-casein, the 67th amino acid in the series is proline. All other amino acids in the structure are indistinguishable. Yet, these two ever-so-slightly different versions of otherwise identical proteins behave very differently in the body. It's incredible how much of a difference a single amino acid can make.


Ancient cows of African and Asian genealogies only produced A2 proteins. Their contemporary descendants include Guernsey and Jersey cattle. It seems that the histidine-proline mutation occurred somewhere in the development of modern commercial cattle, notably the Holstein, Ayrshire, and Red cattle families. These dairy cows produce milk containing a mix of A1 and A2 proteins.

When the modern A1 proteins break down in digestion, they produce large quantities of a peptide called beta casomorphin-7 (BCM-7). This peptide enters circulation and binds to opiate receptors in the brain and all over the body. Casomorphin's name gives it away. It is literally a morphine compound. The degree to which BCM-7 acts like other opioids is still studied and debated. It does, however, appear that it happens to different degrees based on the individual. Intense cheese cravings could indicate that there might be an addictive cycle at work.

Emerging evidence is beginning to paint a clearer picture that many symptoms typically blamed on lactose intolerance, such as diarrhea and stomach cramping, may be caused by excessive BCM-7 morphine peptides. Lactose intolerance has nothing to do with proteins but refers to the body's inability to produce the enzyme lactase that breaks down lactose, a sugar in dairy. It is estimated that around 65% of the population are lactose intolerant, yet dairy continues to be consumed globally. This new evidence suggests it might be the protein casein and not the sugar lactose responsible for many of our digestive woes around dairy.

A double-blind, randomized trial in 2016 compared two groups of dairy-intolerant participants. One group drank only A1 milk, and the other drank only A2 milk for the study duration. The resulting discrepancies were quite pronounced. The A1 group experienced increased GI inflammation, post-digestive discomfort, and decreased cognitive ability compared to the A2 drinkers. Critics point out that A2 milk manufacturers fund much of the research A2 benefits, including the aforementioned study. More research is needed to come to any conclusive results. However, many milk drinkers continue to confirm these reports anecdotally. The truth is, for whatever reason, many people do seem to find A2 milk noticeably more digestible.

Since all types of dairy troubles tend not to be subtle, experimenting with a glass of A2 may quickly give you an answer on how your body handles this type of milk. In some cases, people who have given up on milk for years are delighted to find they can now drink a whole glass of A2 milk without problems.

It's worth keeping in mind that switching to A2 milk will still not address true lactose intolerance. Nor will it be appropriate for someone with an established allergy to whey or casein. If you have a mild sensitivity to dairy, you might be curious to see if A2 is the solution that lets you have your milk and drink it too.

Damien ZielinskiA cloud-based functional medicine practitioner with a focus on mental health and insomnia
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