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MILK - Questions and Answers on ‘A1’ and ‘A2’

What’s the difference between ‘A1’ and ‘A2’ milk?

The name comes from the type of protein in the milk. Milk from cows, and any other milk producing animal, can vary quite a lot in the types and amounts of proteins they contain.

Cow’s milk contains six major proteins. Four are casein proteins, the other two are whey proteins. Casein proteins make up about 80 percent of the protein in cow’s milk. A type of casein called beta-casein is one of the major ones, and is itself of different kinds, depending on the genetic make-up of the cow. The most common are beta-casein A1 and beta-casein A2. Milk high in beta-casein A1 is being referred to as ‘A1 milk’ while milk high in beta-casein A2 is being called ‘A2 milk’.

What milk am I drinking?

Milk produced in New Zealand and many other countries normally contains a mixture of A1 and A2 beta-caseins. Different breeds can produce different milk. For example Friesian cows produce mostly A1 milk, while Guernsey cows, sheep and goats produce mostly A2 milk.

Should I stop drinking milk?

No. Milk is nutritious and beneficial and should remain part of a balanced diet.

What is the issue?

Research recently published in the New Zealand Medical Journal has suggested there is a possible link between milk protein consumption and heart disease and insulin-dependent diabetes. Researchers Dr Murray Laugeson and Professor Emeritus Bob Elliott collected data from various sources from 20 wealthy countries and reported a significant correlation between the amount of A1 beta-casein consumed in a country and the national rate of coronary heart disease. They also found a similar correlation between A1 beta-casein consumption and the rate of childhood type 1 diabetes.

What has NZFSA done about this?

NZFSA commissioned an independent expert, Professor Boyd Swinburn, to analyse available published literature on the A1/ A2 issue. That Review is now available. Overall, the NZFSA position continues to be that milk is important in the diet, and there is insufficient evidence to suggest any change to this current advice about the value of milk in the diet. NZFSA will continue to monitor developments and research in the area and seek expert advice if and when such research becomes available.

What is the situation with diabetes?

While the Review comments that the correlations between A1 milk and diabetes in one study are extremely high, the Review also states that such correlations cannot establish cause and effect, that clinical studies in this area are not very helpful and the results from animal studies are mixed. The Review therefore states that this is an area where further research is needed and could be very worthwhile. In light of this, NZFSA considers that there is not enough evidence to date on which to change positions about the exposure of people to types of milk. NZFSA will continue to seek independent expert advice on new information arising on this issue.

What is the situation with heart disease?

The Review states that cardiovascular disease is a multi-factorial disease. This means that there are many risk factors, supported by a wealth of evidence, that need to be addressed. The review suggests that one of the dangers of focusing on new potential risk factors with marginal evidence is that the important other major risk factors with good evidence are forgotten. Major risk factors include smoking and high saturated fat intake; major risk mitigating factors include omega-3 fatty acid, and fruit and vegetable consumption.

The studies available do not provide sufficient evidence to support changing advice on the consumption of milk.

What is the situation with neurological disorders?

Schizophrenia: The Review identified only one study related to the issue, and found no evidence of any causal relationship.

Autism: The Review identified a number of studies of ‘casein-free’ diets in people with autism, but all were associated with gluten-free diet as well. While the available evidence is suggestive that reducing casein and gluten in the diets of people with autism might play a role in improving behaviours, further research is needed.

The studies available do not provide sufficient evidence to support changing advice on the consumption of milk.

What is the difference between ‘correlation’ and ‘cause and effect’?

A correlation indicates that there may be a relationship between two things, but can not be taken as evidence that one of things causes the other (‘cause and effect’). For example, in New Zealand there is an extremely strong correlation between people who buy a car and later in life buy a home. Clearly, though, buying a car in your youth doesn’t ‘cause’ you to buy a home later in life.

Scientists look for correlations in order to help them discover possible causes for certain effects. They then conduct experiments and studies to see whether the relationship proves to be true or significant.

What is a multi-factorial disease?

A multi-factorial disease is one that has more than one cause. Heart disease is a good example. Diet, smoking and drinking, as well as a family history of heart disease, have all been shown to be causes, or factors in the cause. Not all diseases are multi-factorial. Many foodborne illnesses, for example, are caused by an organism which gives its name to that disease, such as Toxoplasma causing toxoplasmosis.

Where do I look for further information

There is more information on the NZFSA website at:

http://www.nzfsa.govt.nz/policy-law/projects/a1-a2-milk/

See also NZFSA press release A1/A2 milk review released August 3^rd 2004