A1/A2 protein explained
Approximately one third of protein in cows' milk is beta-casein which is comprised of both A1 and A2 beta-casein. These have different outcomes upon digestion when compared to one another due to a slight difference in the amino acid sequence on the peptide chain. A1 beta-casein preferentially releases the opioid peptide beta-casomorphin 7 (BCM-7) on digestion. In contrast, the structure of A2 limits the release of BCM-7 on digestion.