A2 milk is cow's milk that contains only the A2 type of β-casein protein rather than the more prevalent A1 protein commonly found in regular milk. a2 Milk is branded by The a2 Milk Company and sold mostly in Australia, New Zealand and the United Kingdom. There is no consensus that A2 milk has benefits over "A1" milk. A2 milk is not a milk substitute for infants with cow milk protein allergies.
A1 and A2 β-casein are genetic variants of the beta-casein milk protein with different chemical structures. The A1 β-casein type is the most common type found in cow's milk in Europe (excluding France), the USA, Australia and New Zealand.
A genetic test, developed by The a2 Milk Company, determines whether a cow produces the A2 or A1 type protein in its milk. The test uses hair from the cow's tail to determine this. The test allows The a2 Milk Company to give licenses to milk producers once these producers prove their cows produce only A2 β-casein protein in their milk, to the exclusion of the A1 β-casein protein type.
A review of the relevant scientific literature by the European Food Safety Authority (EFSA), published in February 2009, found that "a cause and effect relationship is not established between the dietary intake of BCM7, related peptides or their possible protein precursors and non-communicable diseases".
- 1 February 2009, EFSA review of scientific literature on A1 and A2 milk, Review of the potential health impact of β-casomorphins and related peptides
- Kemp AS, Hill DJ, Allen KJ, Anderson K, Davidson GP, Day AS et al. (2008). "Guidelines for the use of infant formulas to treat cows milk protein allergy: an Australian consensus panel opinion.". Med J Aust 188 (2): 109–12. PMID 18205586.
- EFSA - Scientific Report of EFSA: Review of the potential health impact of β-casomorphins and related peptides. p. 20.
- A license has been given to Robert_Wiseman_Dairies to produce A2 Milk in the UK.
- Swinburn B, 2004. Beta casein A1 and A2 in milk and human health. Report to New Zealand Food Safety Authority
- Beta-casein A1 and A2 in milk and human health: NZFSA Lay Summary
- Millward, C; Ferriter, M; Calver, S; Connell-Jones, G (2008). "Gluten- and casein-free diets for autistic spectrum disorder". In Ferriter, Michael. Cochrane database of systematic reviews (Online) (2): CD003498. doi:10.1002/14651858.CD003498.pub3. PMID 18425890.