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A2 Milk is a trademark of the A2 Corporation, which is licensed by milk distributors to apply to cows' milk which has been tested to ensure it contains a higher proportion of A2 type β-casein than regular milk. The A2 Corporation has developed a test, where DNA from a cow's tail hair is examined to determine whether the milk they produce will be high in the A2 protein. Milk producers can test all their cows, and separate those that produce A2 milk from those who do not. Milk identified as "A2 milk" is currently available in New Zealand, Australia and select locations in the United States.

About a third of the protein in cows' milk is β-casein and there are several forms of it.

Directly from the A2 Corporation website: "It was recognized that this statistical correlation was not, in itself, proof of a beneficial effect..."

In Devil in the Milk, Craig Potton Publishing, Nelson, 2007, Professor Keith Woodford explains the differences between 'normal' milk and A2 milk as follows:

Some thousands of years ago a genetically different strain of milk appeared, now known as 'A1' milk. The original 'A2' milk is generally produced by cattle in Africa, Asia, France and Guernesy. Goat and camel milk is also 'A2'. Cattle in other countries generally produce mainly 'A1' milk.

There is only one genetic difference between A1 and A2 milk, being the amino acid at position 67 in the chain of 209 amino acids that make up beta-casein protein in milk. “In the case of A1 beta-casein the amino acid at position 67 is histidine, whereas with A2 beta-casein it is the amino acid proline.” (p 37)

However this small difference results in the milk having quite a different chemical - and perhaps physiological - effect. This is because the proline forms a strong bond with the amino acids in positions 66 and 68. In A1 milk, the histidine linkage with its neighbours is more “easily broken by digestive enzymes.”(p37) The breakdown of these links through digestion creates a protein fragment known as BCM7 (beta-casomorphin-7) which acts as an opiate. (p37)

BCM7 is not created by digestion of A2 milk because of the different amino acid at position 67 in the bea-casein protein chain.

Both A1 milk and BCM7 have been associated with plaque formation (p 50 and Chapter 4 generally).

Professor Woodford compares studies of heart disease in countries which consume A1 milk and countries which consume A2 milk and finds a strong correlation between consumption of A1 milk and heart disease (Chapter 3 generally and see the chart on p 54).

He also finds a correlation between heart disease and type 1 diabetes (p 51 and Chapter 5 generally). He suggests that A1 milk may be implicated in a range of other physical and mental problems (See Chapters 8 and 9 generally).

If the different types of milk are taken into account, this could (rather than the red wine hypothesis) explain why the French (and the Masai), while having high dairy diets, have comparatively low levels of heart disease (pp 57 - 59). In each case, those persons would appear to consume only A2 milk. The Finns, on the other hand, have high dairy diets but consume predominantly A1 milk - and have high levels of heart disease (p59).

External links

• A2 Corporation Website
• A2 milk science website
• Information on beta caseins
• A2 Australia Pty Limited
• NZFSA Lay Summary
• NZFSA Peer Review
• A1 Milk and Heart Disease/Diabetes/Beta Casmorphin 7
• ABC TV Australia's "Four Corners" investigation, "White Mischief"
• You may be asking, “What is a2 Milk?” - Hy-Vee
• A1 and A2 Milk (14 September 2007) Fact Sheets 2007 - Food Standards Australia New Zealand
• A2 Milk - FactSheet - Food Intolerance Network

Keith Woodford, Devil in the Milk, Craig Potton Publishing, Nelson, 2007

• Milk