A2 Milk

A2 Milk, within this Knowledge Codex, refers specifically to milk produced by indigenous Indian cattle (Bos indicus) that carries the A2 allele homozygously at the CSN2 locus encoding beta-casein. This is categorically distinct from branded commercial A2 milk products produced by selected taurine breeds in other markets. The A2/A1 distinction is a single-nucleotide polymorphism resulting in a proline-to-histidine substitution at codon 67 of the CSN2 gene. This substitution has documented downstream consequences for protease-mediated peptide release during digestion (CLM-102).

Verified Claims Register

  • [CLM-101] Indigenous Indian cattle breeds display a near-uniform frequency of the A2 allele at the CSN2 locus, producing milk protein that differs from A1 beta-casein at position 67 (proline vs. histidine). Scientific Evidence
  • [CLM-102] The proline residue at position 67 of A2 beta-casein creates a local conformation resistant to enzymatic cleavage, preventing release of the BCM-7 opioid peptide fragment during gastrointestinal digestion. Scientific Evidence

Provenance

[CLM-101] Sodhi M, Mukesh M, Kataria RS, Mishra BP, Joshi BK. Note on milk protein genetic variants of native Indian cattle (Bos indicus) and buffalo breeds. Journal of the Indian Society of Animal Sciences. 2012;16(Suppl 2):S856. DOI: 10.4103/2230-8210.104832
[CLM-102] European Food Safety Authority. Review of the potential health impact of beta-casomorphins and related peptides. EFSA Scientific Report. 2009;231:1–107. Available at: http://www.efsa.europa.eu/en/supporting/pub/ce231e.htm