Full Name: A1 Casein
Synonyms: A1-CS
A1 casein is a genetic variant of beta-casein protein found in cow milk. Cleavage of A1 casein during gastrointestinal digestion releases beta-casomorphin-7 (BCM-7), an opioid peptide linked to digestive discomfort in sensitive consumers. Its primary structure differs from A2 casein by a single amino acid substitution (histidine instead of proline at position 67).