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Book Data

ISBN: 9781603581028
Year Added to Catalog: 2008
Book Format: Paperback
Dimensions: 6 x 9
Number of Pages: 252
Book Publisher: Chelsea Green Publishing
Release Date: March 8, 2009
Web Product ID: 445

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Devil in the Milk

Illness, Health, and the Politics of A1 and A2 Milk

by Keith Woodford

Foreword by Thomas Cowan, MD

Author Q & A

In Devil in the Milk, you write about a little-known but harmful protein in a certain kind of milk known as A1. What is A1 milk?

A1 milk is “shorthand” for milk in which some of the protein is of a type called A1 beta-casein. The alternative protein is A2 beta-casein. Originally, all beta-casein was A2 until a chance mutation occurred some thousand of years ago. This mutation has affected a lot of cows of European origin. North American herds will typically contain a mix of A1 and A2 producing cows. In effect, A1 milk is ‘ordinary milk’ containing a mix of both proteins. So A1 milk will contain a mix of the A1 and A2 beta-caseins, whereas A2 milk is from selected cows that only produce the A2 variant of the protein. (Actually there are also other less common variants with other names, some of which act like A1 and others like A2. So when we say “A1” we really mean all the variants that act like A1 and likewise for A2.)

How can A1 affect human health?

When A1 beta-casein protein is digested it breaks down to form a protein fragment called beta-casomorphin7. Usually we abbreviate this to “BCM7.” This BCM7 is an opioid and is what I call the “milk devil.” In many people it further breaks down and does no harm, but it seems that in some people it passes through into the bloodstream. Among developed countries, those countries where there is a high intake of A1 beta-casein are the same countries that have a high incidence of Type 1 diabetes (the type for which insulin is necessary and the main form of diabetes in children). These countries are also the ones that have high levels of heart disease. Other countries, with similar high income lifestyles but lower A1 beta-casein, have much lower levels of these diseases. Susceptible mice and rats fed A1 beta-casein developed very high rates of Type 1 diabetes whereas those fed A2 did not. Rabbits fed A1 beta-casein developed arterial plaque at much higher levels than those fed A2. A1 beta-casein has also been implicated in making the symptoms of autism worse. Many people who cannot drink ordinary milk because it causes diarrhea, nausea, rashes or stuffy noses, find they can drink A2 milk without trouble.

Is A1 the only type of milk on the market? How can I find alternatives?

In North America it is currently not possible to purchase milk that is guaranteed to be A2, although that may soon change. In Australia and New Zealand we have selected dairy herds that only produce A2 milk and this is readily available in many supermarkets. Sheep milk and goat milk are of the A2 type, as is human breast milk.

Currently, hardly anyone in the United States knows about the controversy over A1 beta-casein or the push for alternatives. Why do you think this is?

There are two key reasons. One is that it is a complex story. It is not easy to get the message across in 15-second media sound bites. The second is that elements within the dairy industry have been successful in keeping the information “below the radar” and in some cases disseminating misleading information. But all of the key evidence in my book comes from peer reviewed articles in major scientific and medical journals. All that I have done is to put that information together and also to expose some of the misinformation.

Is the A1 beta-casein protein in cows genetically inherited?

Yes. The gene that determines the type of beta-casein is on the sixth chromosome. Cows and bulls carry two copies of this gene. So a cow can carry either two copies of the A1 variant or two copies of the A2 variant, or one copy of each. Neither variant dominates over the other. This means that a cow that has one copy of each variant will produce A1 and A2 beta-casein in equal quantities. A cow that has two copies of the same variant will only produce beta-casein of that type.

A cow passes on one copy of the gene to her progeny and the bull provides the other copy. If an animal carries one copy of each variant, then it is a matter of chance as to which is passed on.

Can dairies with A1-producing cows switch over to A2-producing cows? How long would it take and how costly would it be?

It would take about two cow generations, or about ten years, to convert the entire North American herds to becoming predominantly A2. This could be achieved by using only DNA-tested bulls that carry double copies of the A2 variant. These bulls are therefore guaranteed to pass on an A2 copy of the gene to all of their progeny. However, the first generation progeny may still pick up an A1 variant of the gene from their mother. Individual farmers can therefore speed up the process by DNA testing their cows and calves, and selecting accordingly. Indeed total elimination of the A1 variant cannot be achieved without DNA testing of females. In Australia and New Zealand some farmers have been able to very quickly form pure herds by buying additional DNA-selected cows.

The cheapest way of doing the conversion is to use A2 bulls for semen. This has minimal cash cost but it is also the slowest way. But any progress is good progress for overall population health.

No one can tell just by looking at either the milk or the cows as to whether it is A1 or A2. Cows of any common breed may be either A1 or A2, although some breeds are higher in A2 than others. It is only by testing the individual cow or the milk that this can be known. Currently this test is not commercially available in the United States but it is not a difficult test. In the meantime, I believe that some North American herds are being tested by sending the DNA samples to New Zealand.

Is A1 milk an issue among dairy farmers who operate within organic regulations, or just among cows farmed “conventionally”?

The A1 and A2 issue is relevant to both organic and conventional dairy farms. In New Zealand we have an organic dairy farmer who has also selected for A2 and distributes his milk widely throughout the country.

You have received much praise for your groundbreaking research, and your book has been compared to Ralph Nader’s Unsafe at Any Speed and Rachel Carson’s Silent Spring. Have there been any efforts by the dairy industry or the government to bury this issue, or deny your evidence?

Yes. There has been opposition. Some of it has been by people who genuinely believe it is a non issue. But in general those people have been misled by incorrect information. Elements within the dairy industry have very sophisticated public relations programs that are international in their impact. One approach has been to disseminate “below the radar” communications to opinion leaders. These documents never themselves appear in public, where they can be refuted, but they do influence the opinion leaders. Another strategy is for supposedly independent experts to make public statements without acknowledging that they work as dairy industry consultants in relation to the A1 and A2 issue. Given the complexity of the scientific issues, it has been easy for those who wish to muddy the waters to do so. Other people then pass on the misinformation in good faith. From within the dairy industry and even from within government I get many comments along the lines: “but we must not do anything that would damage the dairy industry.” Often they then get very upset when I say that is exactly the approach the tobacco industry took.

In your book you also raise issues of scientific integrity. What are these issues?

The key issue relates to a scientific trial published in the international journal Diabetologia. It is this trial that is the most widely used argument about A1 and A2 milk. The trial involved feeding A1 and A2 beta-casein to diabetes-susceptible rats and mice in three different countries (Britain, Canada, and New Zealand). All of the diets came from New Zealand. Unfortunately, the diets were contaminated by adding an infant formula powder to both the A1 and A2. Owing to a manufacturing problem, this infant formula contained BCM7, which was the exact hypothesized source of the problem in the A1. It is an almost unbelievable error but it happened! Not surprisingly, the rodents fed contaminated diets showed no statistically significant difference for diabetes incidence between the A1 and A2 diets. The contamination was known more than one year before the paper was published but the contamination has never been acknowledged publicly. In my book I provide the documentation, including a confidential internal document from the New Zealand Dairy Research Institute which provided the diets, together with email correspondence between authors of the paper in which prior knowledge of the contamination is privately admitted. The ongoing nondisclosure is a huge issue of scientific integrity. The international dairy industry keeps using this paper as evidence that the effects of A1 milk have been disproven. Even the European Food Safety Authority has used this paper as evidence to downplay the link to Type 1 diabetes.

Why did you become interested in the A1 /A2 issue?

As a Professor of Agribusiness I am always interested in food issues. But I had ignored the A1/A2 issue because our mainstream New Zealand dairy industry said it was simply a “beat up” and I believed them. Then a former colleague of mine became a Director of the A2 Corporation and that attracted my attention. I looked more closely and was amazed at what I found. I was also annoyed at the way that scientific information about the issue was being managed and massaged. From a personal and career perspective, I realized the smart thing was to keep my head down and say nothing. By sticking my head up above the parapet I knew that life would never again be quite so simple. But it seemed something I had to do.

Where can people read more about the A1 issue?

Well, hopefully they will read my book where I set out the evidence from more than 100 individual pieces of research. The book is not just about science, but how society uses and at times twists that science.

People may also like to read an invited plenary paper I gave to the International Diabetes Federation Western Pacific Congress in April 2008. This is available on the internet at


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