A2 caseins have been shown to cause gastrointestinal inflammation
Research suggests that A1 caseins may be harmful to the gut in ways that A2 caseins are not. In 2016, a team led by Sun Jianqin studied forty-five participants who consumed milk containing both A1 and A2 milk proteins, and then milk containing only A2 casein. The researchers found that when subjects drank milk containing A1 casein, they had more gastrointestinal inflammation, their thinking was slower, and they made more errors on an information-processing test.
Luckily there is milk available that only has A2 casein. Milk from breeds of cows that originated in Northern Europe is generally high in A1 casein. These breeds include Holstein, Friesian, Ayrshire, and British shorthorn. Milk that is high in A2 casein is mainly found in breeds that originated in the Channel Islands and southern France. These include Guernsey, Jersey, Charolais, and Limousin cows. Sheep’s and goats’ milk is generally A2 casein milk. You can also try nut milks and milk nut yogurts as a way to avoid A2 casein.
References
- Naidoo, Uma. (2020). This is Your Brain on Food Chapter 5. ADHD Gluten, Milk Caseins, and Polyphenols (p. 141). New York, NY: Little Brown Spark.