The A1 vs. A2 Milk Story 

December 2007

In mid 2007, Keith Woodford’s book, Devil in the Milk, hit the book shops, creating a burst of publicity about the link between the type of milk New Zealanders drink and a range of serious illnesses, including heart disease, Type 1 diabetes, autism and schizophrenia. The story starts with the remarkable epidemiological evidence demonstrating the strong association between countries that have a high intake of A1 milk and a high incidence of both Type 1 diabetes and heart disease.

The book revealed how these diseases and a number of other health problems are linked to a tiny protein fragment that is formed during the digestion of the A1 beta-casein, a milk protein produced by cows in New Zealand, Australia and many other western countries. Milk that contains A1 beta-casein is known as A1 milk, whereas milk that is not is called A2 milk. Originally all milk was A2 until a mutation affecting some European cattle occurred some thousands of years ago. Herds in much of Asia, Africa and part of southern Europe remain naturally high in A2 cows.


The effects on human health of this tiny protein fragment called beta-casomorphin-7 (BCM7), which is a powerful opioid or narcotic as well as being an oxidant, are explained very clearly and simply by Keith Woodford, Professor of Farm Management and Agribusiness at Lincoln University in New Zealand. He brings together the evidence published in more than 100 scientific papers, examines both the population studies and the research undertaken with animals and humans, and explains the science that under-pins the A1/A2 hypothesis. He also points to the increasing evidence that BCM7 is associated with milk intolerance and an additional range of auto-immune diseases, including Type 1 diabetes, an auto-immune disease in which the body destroys its own insulin-producing cells. Type 1 diabetes usually occurs in childhood or early adulthood. 

Human Milk vs Cows Milk

The book contained a number of references to the differences between human milk and cows milk and the impact this can have on the health and future well-being of babies. One of the differences has to do with protein differences. As Keith Woodford explained:

The protein level of human milk is about 1.6% in the first few days following birth and then drops to about 0.9%. In comparison, bovine milk is typically 3-4%, depending on both the breed and individual differences. The specific balance between the proteins is also quite different. In bovine milk about 80% of the proteins are casein proteins whereas in humans the major proteins are whey proteins.”1

There is also an important difference between the human casein protein and the beta-casein produced by cows. All human beta-casein is more like the A2 type rather than the A1 type which means that human milk releases much less BCM7. When testing human milk, New Zealand researchers found that they got less than 1% of the BCM7 that could be released from the same amount of A1 milk, meaning that when it comes to the relative opioid effect, human milk has less than one-thousandth the potential potency of A1 cows’ milk.

Leaky Gut Syndrome

Part of the puzzle of how BCM7 gets into the bloodstream involves what happens to BCM7 when it is released into the gut. It should be difficult for BCM7 to get through the gut wall and into the bloodstream because the molecule is too large. However, some people suffer from leaky gut syndrome which enables BCM7 and other peptides to pass very easily through the gut wall and into the bloodstream.

Keith Woodford described how in people with a leaky gut it is possible to detect BCM7 in the urine. He stated that this condition has been closely associated with the symptoms of autism and schizophrenia due to the known opioid effects of BCM7, an association confirmed by the presence of BCM7 in their urine.

There is also very strong circumstantial evidence that people with stomach ulcers or untreated coeliac disease absorb BCM7 through the gut wall. It is also likely that babies can absorb BCM7 the same way; in fact newborn babies need to be able to pass large molecules through the gut wall. Otherwise they would not be able to absorb the colostrum in their mother’s milk.”1

 Effects of BCM7 on Babies

If newborns are able to pass large molecules through the gut wall then this increases their vulnerability and susceptibility to the effects of BCM7 in A1 milk and to infant milk formula products made with A1 milk. Early and prolonged exposure to BCM7 in infant formulas may therefore be a significant factor in the rising incidence of autism, Asperger’s syndrome, Type 1 diabetes, heart disease, and a range of other auto-immune diseases. Research on the presence of BCM7 in infant formula has not been done and is urgently needed.

It is also not known whether BCM7 is likely to be a problem in cheese, or in ice-cream, yoghurt, and various other milk products. Until the research has been done, New Zealand consumers need to be aware that they may also pose similar risks to health that drinking A1 milk does.

The Solution

The solution to the problem is both simple and unbelievably cheap. All that is required is for farmers to ensure that their cows are inseminated, naturally or artificially, with semen from A2A2 bulls. Given the majority of top bulls in New Zealand happen to be A2A2 this would not be difficult. Some of the smaller groups of New Zealand dairy farmers, predicting the increase in consumer demand for A2 milk, have already converted their herds to A2 cows. An added bonus for them is that some recently published research revealed than on average New Zealand A2 cows actually produce more milk than A1 cows. Keith Woodford has calculated that if farmers used only A2A2 bull semen for their herds it would take less than a decade to make the switch.

The question that then springs to mind is why has this not been carried out already? This is where the politics of public health and the vested interests of big business come into conflict.

New Zealand Food Standards Authority

The New Zealand Food Standards Authority is a government organisation charged with both protecting and promoting public health and safety, and facilitating access to markets for New Zealand food and food products. Herein lies the most astounding conflict of interest one could imagine.

NZFSA’s response to the link between the consumption of A1 milk and Type 1 diabetes and heart disease raised in the publication of a paper by Dr Murray Laugeson and Professor Bob Elliott in the NZ Medical Journal in early 2003 demonstrated very clearly that in the battle between the interests of the dairy industry and those of public health, the industry’s interests won hands down. NZFSA attempted to put a lid on this particular Pandora’s box.

In 2003 Fonterra/the dairy industry and A2 Corporation were slogging it out in the courts, as A2 Corporation was claiming that ordinary milk should carry a health warning. Not an unreasonable position for the A2 Corporation to take, notwithstanding their vested interests in the issue.

Only two years prior to this – in September 2001 to be exact – Fonterra in its previous incarnation as the NZ Dairy Research Institute had applied for a patent claiming that A1 beta-casein was associated the death from mental illnesses in general, and was strongly associated with autism in particular. This was because it was believed that BCM7 “may induce or aggravate a neurological/mental disorder such as autism or Asperger’s syndrome.”  Epidemiology from 10 countries revealed that intake of A1 milk correlated very closely with WHO data on the level of deaths from mental disorders in those countries. The NZDRI’s patent application was subsequently abandoned.

During the years between the publication of the paper by Laugeson and Elliott in the NZ Medical Journal and the publication of Keith Woodford’s book, the NZFSA has continued to place the interests of the dairy industry above the considerable public health issues that the continuing consumption of A1 milk represents to the New Zealand public.

In conclusion, the A2 milk story is truly an amazing tale, one that is not just about the health issues surrounding A1 milk. It is also a story that reveals how scientific evidence can be moulded and withheld by vested interests, and how consumer choices are influenced and manipulated by the interests of corporate business.


1. Devil in the Milk by Keith Woodford 2007. Craig Potton Publishing.

Two Reviews on the A1/A2 Milk Debate

February 2008

In mid December 2007 Food Safety Minister Lianne Dalziel announced two reviews into the food safety implications of A1/A2 milk. An international expert was appointed to head an independent review into the risk management decision-making processes adopted by the NZ Food Safety Authority (NZFSA).

Dr Stuart Slorach, former Chair of the Management Board of the European Food Safety Agency (EFSA), began work immediately, the Terms of Reference for the review of the NZFSA’s risk management decision-making processes having already been considered by the State Services Commission. Three of the eight terms of reference focused on Professor Boyd Swinburn’s report, Beta-casein A1 and A2 in milk and human health, the NZFSA’s response to the report, the delayed release of the lay summary prepared by Professor Swinburn and his non-availability to respond to media queries resulting from the release of his report. There are repeated references to risk management and risk management systems but little about the public’s right to information on which to make their own decisions.

The Cabinet paper on the arrangements for the two reviews stated that “NZFSA prepared these Terms of Reference” for the first review and consulted with the Ministry of Health over the Terms of Reference for the review of the science. The fact that NZFSA played such a major role in the reviews called into question how much credibility can be attached to the outcome of either review. 

On 1 February 2008 the NZFSA announced that first stage of Dr Slorach’s review was almost completed. After two weeks in New Zealand Dr Slorach returned to Europe, where he visited the government food safety agencies of Ireland, Denmark and Sweden. Having been carefully shepherded around New Zealand by the NZFSA it was hoped that Dr Slorach had considerably more independence when he visited the European food safety agencies.

Dr Slorach returned to New Zealand in late March 2008 to finalise his review. His report was required to include a description of the NZFSA system, a description of international best practice in the area, a comparison between the NZFSA system and best practice, and a commentary on the application in recent risk management decision-making matters.

The second review involved a re-examination of the scientific research relating to A1/A2 milk, and in her December 2007 press release Ms Dalziel stated that the NZFSA was currently working with the European Food Safety Agency in relation to reviewing the science.

How much involvement the NZFSA had in what the final reports looked like was a major cause for concern.


Read more:

A2 Milk- Minister Gives Reassurance

Farmers Weekly

February 2008

A1 and A2 Milk, and the Slorach Review of NZFSA

Scoop News

April 2008

A2 Milk : A2 report finds good and bad

Farmers Weekly

June 2008

Milk Debate on Review List


February 2009

Warning on NZ Food Safety Watchdog


January 2009

NZFSA urged to admit it erred on milk safety


January 2009

The Industry Politics of A1 and A2 Milk

Keith Woodford

September 2014

A1 beta-casein, Gut Inflammation and Immune Reactions

Keith Woodford

Januray 2014