a2A2

The a2A2 refers to a specific genetic variant of the beta-casein protein found in milk. Beta-casein is one of the main proteins in cow's milk, and it exists in different forms, or genotypes, due to variations in its DNA sequence. The most common genotypes are A1 and A2. The a2A2 designation specifically refers to milk that contains only the A2 variant of beta-casein. This means that an animal producing a2A2 milk has inherited the A2 variant from both parents.

Milk from cows can contain either the A1 variant, the A2 variant, or a combination of both. Historically, most cows produced A2 beta-casein. However, through selective breeding and mutations that occurred over time, the A1 variant became more prevalent in many dairy herds. Milk containing only A2 beta-casein is marketed as a2 Milk, and is often promoted for potential digestive benefits compared to conventional milk which may contain A1 beta-casein. Research into the physiological effects of A1 versus A2 beta-casein is ongoing, with some studies suggesting differences in how these variants are digested and their potential impact on gut health and inflammation. Consumers interested in a2A2 milk often choose it based on perceived improvements in digestive comfort or a desire for milk closer to the ancestral form.