What is a2 milk?

The solids found in cow's milk are composed of fat, protein, lactose and minerals. Beta-casein is one of six milk proteins and is produced by the CSN2 gene. There are 15 different variants of this gene.  Based on the amino acid in position 67 of the CSN2 gene, these variants can be classified into 2 groups, A1 and A2. 

When metabolized, beta-casein produces a bioactive peptide called beta-casomorphin 7 (BCM7). In A1 milk, the BCM7 levels released are several-fold higher than in A2 only milk. 

These higher levels of BCM7 have been associated with negative health effects in humans. Many people who otherwise cannot tolerate milk have been able to drink A2 milk without any issues. 

Historically, all cow's milk was A2/A2 but over time the A1 variant developed and now the majority of cows are mixed A1/A2. Our herdshare cows have all been tested to have A2/A2 genetics. 

If you'd like to learn more about the health implications of A1 vs. A2 milk I strongly suggest reading Prof. Keith Woodford's book, "The Devil in the Milk" and also his many articles written on his page.