Beta Casein

About 30% of the nutritionally important protein in cows' milk is beta-casein. Research indicates that originally all cows produced milk containing only the A2 type of beta-casein, but at some point in history, owing to natural genetic mutation, a variant of the A2 gene and its associated protein appeared. Termed the A1 variant, it differed very slightly in composition from the original A2 beta-casein and has since given rise to a number of minor related subvariants, such as those termed B and C.

Beta caseins are important in the transport of essential ions such as iron, calcium, zinc and copper. It is known that the beta caseins, when digested can yield a plethora of bioactive protein fragments, a number of which have been well characterised with regard to potential biological activity. The small differences between the beta casein variants can lead to the differential digestion of them when consumed, and thus a different yield of bioactives; it is this phenomenon which a2 Corporation Ltd believes is important when seeking to maximize the benefits of milk.

The A1 beta-casein and related sub-variants in cows’ milk, when digested, are known to produce a protein fragment (peptide) with strong opioid properties known as BCM-7. Recently the focus of numerous international studies, BCM-7 is widely believed to have the potential to interfere with the immune system in people with particular genetic susceptibilities. It has also been shown to catalyse the formation of oxidised LDL, an established risk factor in the development of arterial problems leading to coronary heart disease. Other studies have indicated an apparent connection between BCM-7 and the aggravation of neurological disorders including autism and schizophrenia.

a2 Milk™ yields a minimal level of BCM-7 when consumed, and thus the risks associated with it in susceptible consumers may be avoided. This is the scientific basis for asserting that on the basis of growing research that a2 Milk™ consumption may present additional advantages to some consumers. In 2004 the New Zealand Food Safety Authority published an independent review of the scientific work undertaken internationally on issues relating to a2 Milk™, authored by Professor Boyd Swinburn. An independent lay summary of research behind a2 Milk™ from the New Zealand Food Safety Authority Beta casein A1 and A2 in milk and human health concluded:

"The A1/A2 hypothesis is both intriguing and potentially very important for population health if it is proved correct. It should be taken seriously and further research is needed".

The research is far from complete and is ongoing, but results to date suggest not only a statistical link but also a mechanism by which the consumption of beta-casein variants has different effects on susceptible individuals.



The A2 type is regarded by many studies as the original form of bovine beta-casein as consumed by humans thousands of years ago. Through natural genetic mutation over the millennia other variant beta-casein types evolved from the original type, A2. The milk from certified A2 cows is referred to as 'a2 Milk™