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.

Cow’s milk A1/A2 beta-casein digestion protein digestion

Cows’ milk A1 and A2 beta-casein type protein digestion infographic

An infographic providing an overview of the A1 and A2 beta-casein protein variants. The graphic displays how upon consumption of regular milk which contains A1 beta-casein protein, BCM-7 is released resulting in gastrointestinal differences.

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*A1 and A2 proteins refer to A1 and A2 beta-casein protein types

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An association between consumption of 3 serves of dairy foods containing A1 beta-casein and digestive discomfort, in some individuals, has been established by a process of systematic review. The NHMRC recommends a healthy diet including up to 4 serves of dairy foods/day.