You may have noticed that there is now A2 milk available in some of the grocery stores. A2 milk is the original gene that milk protein had centuries ago. Modern dairy is a combination of A1, or A1/A2 dairy proteins, specifically beta-caseins. What we know about milk that contains A1/A2 proteins is that this milk is harder to digest and for some people it can cause inflammation. Digestive problems include stomach upset, and indigestion. The reason that A1/A2 mixed proteins cause inflammation is that on ingestion a pro-inflammatory compound called beta-casomorphine is produced. Beta-casomorphine can produce symptoms such as bloating, gas, and pain. Beta-casomorphine is not easily produced in milk containing only A2 protein.
The breeds of cows that are more likely to be A2 are Jersey, Charolais, Brown Swiss, Guernsey, and Normandy. Milk cows that are genetically A2/A2, will only produce A2 milk. To determine if a cow is A2, the hair from a cow is genetically tested. The results will be any of the following, A1/A1, A1/A2, or A2/A2. Currently, there is testing and breeding to develop dairy herds of the Holstein breed that are A2/A2 to deliver A2 milk.
In 2019 a paper was published in Journal of Pediatric Gastroenterology and Nutrition, that showed that the protein of A1 milk, caused more negative effects in preschool children than the milk with A2 protein. This study found that the children consuming the milk that contained the A1 protein experienced increased stomach discomfort, unusual stool constancy, less desirable fatty acids were produced in their digestive tract, and they had increased beta-casomorphine in their blood. These children also had increased inflammation markers in their blood, and their cognitive performance was impaired. This study is important in that it confirmed the findings of other studies.
There are so many recipes that use milk. Using a A2 milk for cooking can be a good idea for ease of digestibility. I have found that very few local grocery stores carry A2 milk, so it may require consumers, speaking with the employees that order the dairy for the store, to be asked to bring it in. I have been using A2 milk for about two years, and I really prefer it. Currently, the only A2 dairy products that I have found are 1 percent, 2 percent, and 3 percent milk in 2 liter cartons.