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What are A2 Milk Proteins?

Milk consists of two major proteins, casein and whey. Approximately one-third of the protein consists of beta-caseins, where there are two main types, known as A1 and A2 beta-casein. The concentrations of A1 and A2 proteins in milk vary between different species of cattle and depend on the genetic makeup of the cow. Some cattle can produce either completely A1 beta-casein, a combination of both, or completely A2 beta-casein. Consequently, milk containing a higher concentration of A1 protein is known as A1 milk or regular milk, while milk containing predominantly A2 protein is known as A2 beta-casein milk. The milk sourced for Beta Genica–8™ Toddler Milk is made exclusively from organic A2 beta-casein milk.

A1 and A2 proteins have different structures on the amino acid strand and because of the difference, these proteins are broken down and digested differently. Specifically, when the A1 protein is broken down, it releases a bioactive opioid peptide called beta casomorphin-7 (BCM-7), while the A2 beta-casein protein does not. It is thought this difference means some people poorly tolerate milk. Studies in humans show that people who experience digestive discomfort symptoms drinking regular cow’s milk, may be able to consume milk containing only the A2 beta-casein protein without adverse effects. A recent study of children with self-reported mild to moderate discomfort following milk consumption showed replacing regular milk with A2 beta-casein milk reduced gastrointestinal symptoms.



1. Scientific Report of EFSA prepared by DATEX Working Group on the protein health impact of β-casomorphins and related peptides. EFSA Scientific Report (2009). 231, 1-107. URL: http://edepot.wur.nl/8139

2. Pal S, Woodford K, Kukuljan S, Ho S. Milk Intolerance, Beta-Casein and Lactose. Nutrients. 2015;7(9):7285-97.

3. Ho S, Woodford K, Kukuljan S, Pal S. Comparative effects of A1 versus A2 b-casein on gastrointestinal measures: a blinded randomised cross over pilot study. European Journal of Clinical Nutrition. 2014. 68. 995-1000.

4. Sheng X, Li Z, Ni J, Yelland G. Effects of conventional milk versus milk containing only A2 b-casein on digestion in Chinese children: A randomised study. Journal of Pediatric Gastroenterology and Nutrition. 2019. 69; 375-382.

5. Brooke-Taylor S, Dwyer K, Woodford K, Kost N. Systematic Review of the Gastrointestinal Effects of A1 Compared with A2 beta-Casein. Adv Nutr. 2017;8(5):739-48.