A Discussion of the Difference Between A1 and A2 Milk. 

By Craig Turczynski, Ph.D. 

Back when I lived on the farm in Iowa we produced corn, oats and alfalfa and raised beef and pork to earn a living, but we also, kept chickens, sheep and a dairy cow for our own food consumption. The dairy cow we kept was named Ruby and she was a Jersey. We milked her by hand twice a day, every day and consumed her milk raw. The cream we got from her was either made into butter or used with coffee. I also worked for a large dairy farm as a senior in high school and later, a corporation that serviced the dairy industry. The primary type of dairy cow on these large dairy farms was the Holstein. The company I worked for provided the artificial insemination service, which is what most dairy farms used to breed their cows, and I was responsible for picking the sire to breed to each individual cow to maximize production. We knew very little about A1 and A2 casein in those days and since the emphasis was on production, we didn’t breed for it and probably contributed to the genetic transformation of milk production to the A1 variety. Little did I know that the milk we were consuming from our Jersey cow, had different proteins from the milk being produced in the large dairies I worked in. Fortunately, we were doing the right thing for our health, as it turns out. You see, evidence is growing, that milk contains different casein proteins and the A2 variety is found more frequently in Jersey and Guernsey breeds and the A1 variety has become more prevalent in the high producing Holstein breed. The reason for this is that the Holstein, being the favored cow in the industry, was bred more aggressively, passing on the genes for the A1 casein down each generation.

What is the difference between A1 and A2 casein?

Milk is made up of mostly water, with about 13% being fats, protein, lactose (sugar), vitamins and minerals. The protein fraction is 80% casein and 20% whey and other proteins such as enzymes. There are several types of casein proteins but the type most studied has been the Beta-caseins called A1 and A2. The structure of the two are almost identical except for 1 amino acid that is different in the chain of 209 amino acids which make up the casein protein. The 67th amino acid in the chain of A2 casein is Proline and the amino acid in the 67th position on the A1 casein is Histidine. This single amino acid difference between the proteins creates a significant biological consequence. The problem, however, is not with the protein itself, but what happens to it when it is digested. Digestive enzymes will cut the protein into shorter segments, called peptides and when the A1 protein is cut, it forms the peptide called BCM-7, which stands for Beta-casomorphin-7. BCM-7 has opioid-like bioactivity and has been implicated in several health conditions such as heart disease, diabetes and autism. These serious health effects have not been proven and are controversial because much of the research has been supported by a company out of New Zealand called the A2-Milk Company. The A2-Milk Company has protected most of the rights to this intellectual property. There is more evidence for BCM-7 causing gastrointestinal symptoms and is more strongly supported by the scientific community. In fact, some scientists question if the intestinal discomfort commonly thought of as lactose intolerance is due to BCM-7 and not lactose. A study conducted in China and published in the Nutrition Journal in 2016 concluded that gastrointestinal inflammation, discomfort, and delayed transport as well as decreased cognitive function is caused by the consumption of A1 casein but not by A2 casein. An analysis of research on BCM-7 was done in Australia and published in Critical Reviews in Food Science and Nutrition in 2015. The research outlined the relationship between this bioactive peptide and milk processing such as heat treatment and fermentation. Dairy products are subjected to variations in heat treatment (pasteurization) and fermentation depending on if they are used for drinking or the making of cheese or yogurt. While heat treatment is important for control of micro-organisms which cause illness, heat treatment can alter how the proteins are broken down, resulting in fewer natural enzymes and different types of peptides with bioactivity, including BCM-7. This lends support for raw milk because it has not had any of the proteins altered before being consumed. On the other hand, the combination of fermentation and heat treatment during the process of making yogurt, appears to inactivate BCM-7 altogether. Needless to say, there is much we don’t know and much for us to learn.

Should you drink A2 Milk and where do you find it?

The Website www.a2milk.com offers a search engine that allows you to find sources of A2 milk locally. Here in the North Dallas metroplex you can find A2 milk at Wholefoods and Sprouts. I visited both stores and they have half-gallon containers for about $4.00 each. If you currently have gastrointestinal symptoms after drinking milk, it would make sense for you to try it and see if the symptoms persist. The advice about consuming dairy products varies depending on who or what organization you are listening to, so adding the variable of A2 milk will certainly add confusion. Recently, my daughter who is breast feeding her child, was told by one doctor not to consume dairy products to prevent her son from experiencing colic and another said that avoiding it all together was not advised and urged her to re-introduce it. Drinking A2 milk, when she re-introduces dairy to her diet would make sense in her situation since it is related to gastrointestinal symptoms her son was experiencing. Dairy products have been implicated in illnesses ranging from infertility to heart disease and this is because the nutritional content and purity varies significantly based on how the animal is being raised and fed. Drinking A2 milk does not eliminate all potential issues. Right now, it appears it will only alleviate the problem of gastrointestinal issues in some people. As we are learning however, poor gut health and inflammation can lead to other health issues. Since we don’t know anything else about the source of it or what the cows are fed, we don’t know how it compares to other products and how it will address other health issues. We need to know if it is from pastured, organic or non-gmo fed animals to fully understand the product. Ideally, the milk we consume should come from organic, non-gmo or all naturally fed animals for purity, and it should be from pasture raised animals to increase the vitamin, anti-oxidant and omega 3 fat content. The best source of milk would be raw, organic, A2 milk from pasture raised animals. Interestingly, this is what our ancestors drank, just a few generations ago! It appears we have taken a step backwards in that regard. 

References and Additional reading.

Cows Milk-Grass Fed 

The Health Battle Behind America’s Next Milk Trend. 

A2 Milk Wikipedia 

Formation and Degradation of Beta-Casomorphins in Dairy processing.

Effects of milk containing only A2 beta Casein