Caseins are the primary protein in milk (80%), while whey makes up the remaining 20%. Of the 80% caseins, 30% of them are specifically the beta-casein protein.
That’s where A2 comes in. A1 and A2 proteins are both variants of beta-casein protein, and both are commonly found in cow’s milk. Historically, cows produced milk that contained only the A2 form of beta-casein (which more closely resembles human and goat's milk). Somewhere along the line a mutation occurred creating the A1 protein. This A1 protein became more and more prevalent among the higher producing cow varieties and is now found in most milk on the market.
Older cow breeds, particularly Jerseys and Guernseys naturally produce milk with A2 proteins, while Holsteins (black and white) generally produce both A1 and A2. Holsteins are the highest milk volume producing breed and are therefore typically used in commercial dairy operations.
When A1 protein is digested in the small intestine, it produces a peptide called beta-casomorphin-7 (BCM-7). The intestines absorb BCM-7 and it passes into the blood. Doctors have linked BCM-7 to stomach discomfort and symptoms similar to those experienced by people with lactose intolerance. Symptoms of stomach discomfort, gas, bloating, and diarrhea after consuming dairy products, are typically attributed to lactose intolerance. However, some researchers believe that it is BCM-7, not lactose, that is more commonly producing these symptoms. One study
Consuming A2 milk proteins (opposed to A1) has also been linked to lower incidents of cardiovascular disease, type 1 diabetes, and less severe symptoms of autism and schizophrenia.
At Saddle Back Ranch all of our cows are purebred Jerseys (A2 protein producers). They don't give as much milk as higher producing breeds, but it is better milk.
Like all topics, do your own research. We are sure you will be thanking us for sticking to A2.
Milk: It Does a Body Good?