A1 A2 milk gene story too important to ignore

Interest in Beta Casein A2 has skyrocketed since I started testing my cows for this gene back in 2011, so I thought it was time to write a series of blog posts on the topic.

In this post, I describe the composition of milk and the Beta Casein A2 gene and its variants, address the health claims and a common misconception about A2 milk, and discuss how Beta Casein variants may affect cheesemaking.

Milk composition and the A2 gene

Milk is composed of water, lactose, fat, protein, and minerals. The protein content of milk ranges from about 3.1% in Holsteins to roughly 3.8% in Jerseys. Regardless of breed, there are six proteins found in milk: four milk (or casein) proteins—Alpha Casein, Beta Casein, Gamma Casein, and Kappa Casein—and two whey proteins—Alpha Lactalbumin and Beta Lactoglobulin. Beta Caseins account for about 35% of the casein in milk, and 28.7% of total protein.
Beta-casein A2 is a chain of 209 amino acids produced by the CSN2 gene. There are 15 known variants of the A2 gene: A1, A2, A3, B, C, D, E, F, G, H1, H2, I, J, K, and L.

The A2 gene has proline as the amino acid in position 67 (Pro67), while the A1 gene has histidine (His67). Based on the amino acid in position 67, twelve of the fifteen variants have been classified into two groups: A1 and A2. The A1 variants are B, C, F, and G, while the A2 variants are A3, H1, H2, I, J, K, and L. These variants are not identical to A1 or A2 but scientists think they act like A1 or A2 because of the amino acid (histidine or proline) in position 67.

Health claims

When you drink A1 milk, it releases a bioactive peptide called beta-casomorphin 7 (BCM-7) at levels that are four times higher than those found in A2 milk. Scientists think that these high levels of BCM-7 may cause adverse health effects and chronic diseases in humans.

There is anecdotal evidence as well as data from several small human studies, which indicates that about 1 in 4 people are sensitive to the A1 protein, and drinking A1 milk will cause digestive upsets. (In fact, my husband recently discovered that he is sensitive to the A1 protein.)

However, the claims that A1 milk can cause autoimmune and cardiovascular diseases, neurological disorders, and type-1 diabetes are questionable. Nearly all of the studies were conducted in vitro or on rodents. There is a potential conflict of interest as well since the A2 Milk Corporation funded a lot of the research, or employees and consultants of the company conducted it.  (The A2 Milk Corporation owns the patent for the test as well as the trademark for the name 'A2 Milk'.)

Every study and research paper that I read used phrases like 'may cause,' 'may be associated,' 'possible link,' and 'potential risk' when addressing the health claims. Almost every paper ended with a statement that further research and human trials are needed to prove the A1/A2 hypothesis.

A common misconception

​A common misconception is that A1 milk causes lactose intolerance, but all milk has around 5% lactose, whether it's from a cow that is A1A1, A1A2, or A2A2. Also, lactose is a carbohydrate, while Beta Casein is a protein.

Approximately 1 in 6 people have lactose intolerance. This means that they do not produce enough lactase, which is an enzyme that splits lactose into glucose and galactose. Someone who is genuinely lactose intolerant will not be able to digest any milk well without first adding lactase to it.

A lot of people assume that they are lactose intolerant if they can't digest milk well, when they may be A1 sensitive; after all, A1 sensitivity is more common than lactose intolerance. Someone who is A1 sensitive will suddenly be able to enjoy milk again if they switch to A2 milk.
Beta Casein in cheesemaking

Beta Casein plays a critical role in the cheesemaking process and affects both yield and quality. 

The B variant is characterized by an increase in milk casein content and a smaller casein micelle size, which improves the rennet coagulation properties of milk and increases cheese yield.

The A1 and A2 variants can be associated with small or large casein micelle size, but the A1 variant has better rennet coagulation properties.


Organic Pastures Dairy Company LLC

Explanation and Position on A-2 Milk and A-2 Milk Testing

First of all, we love and respect Joe Mercola deeply, but there is a deeper story on A-2 testing.

About five years ago, OPDC attempted to have the A-2 Corporation test all of our cows for A-2 genetic traits. At that time the "A-2 Corporation" was doing business in the Upper Midwest in the USA. The A-2 Corporation refused to test any cows unless all the milk was branded under the A-2 Corporation brand. They also required that all A-2 Corporation milk be pasteurized.   Because OPDC is 100% organic and never pasteurize our raw milk….that was the end of any A-2 testing idea for OPDC. The A-2 testing mandates and ideas broke all of our rules.

About a year ago, OPDC again attempted to contact the A-2 Corporation in an attempt to have its cows tested for A-2 Genetic traits. It was discovered that the A-2 Corporation had gone bankrupt in North America and had just skeletal operations in New Zealand. It took months to get an email through or contact via phone. The answer from A-2 was that they were not providing the patented test to anyone at that time and that perhaps in the future that the test may become available. As of March 2010, the A-2 Corporation is not providing tests to American Dairymen.

There are some people in the raw milk movement that say that they have a way to get cows tested for A-2 traits, but it is questionable whether these tests are actually the original A-2 test and these people want lots of money to do the test.  It is also still very questionable whether the claims made by A-2 are accurate. The authors of "The Devil in the Milk" book claim that cows made a genetic split about 5,000 years ago and that Holsteins and some other breeds were more domesticated because of calmness and other traits ( they were to become more A-1 dominant ). We have no way of knowing that this is true or not. No other research confirms these historical concepts. Also…it is claimed that A-2 cows (Jerseys )produce milk which is far better than cows that are tested and found to be A-1 genetics.

We disagree with this analysis and remain unconvinced of its value. If the split occurred 5000 years ago and A-1 is the source of modern heart disease and makes autism worse….then this does not match up with other researchers at all. Modern diseases began with grain feeding and confinement just 75 to 100 years ago. Modern diseases are much more likely to be associated with modern processing of milk and lack of grass feeding etc.

When evaluating the "67th amino acid" differences in A-2 milk, we ask a much bigger question, when pasteurized milk is observed microscopically it is a massive destruction zone. It looks as if it has been hit with a bomb and everything is dead, broken and twisted. Everything is in little pieces and nothing is alive.

How can a slight 67th position nuance of a single amino acid matter at all in the bigger scheme of massive amino acid changes during pasteurized milk destruction. This makes zero sense.

At OPDC about 50% of our cows are Jersey and 30% are Jersey-Holstein crosses. The rest are Holstein.

At OPDC we believe that the cow is a part of the environment and her milk reflects her conditions and her feed. We feed 100% pastures all of the time. These conditions will reflect in the raw milk that she produces.

Presently, we are being approached to test our cows for A-2 traits by people that do not work for A-2 Corporation. These tests are very expensive and we have no idea what the results would mean or what value they would bring or if they are actually A-2 tests at all? Who knows what they are.

For now, at OPDC, the jury is out on A-2 v. A-1 cows. We are approached every week by people that try to sell us something new to make our products better. We are always open to new ideas….but most of the time we stick with the very oldest of ideas. We stick with mother nature and grass and sunshine. We are not going to slaughter or sell off our perfectly good cows based on one book and a concept which has not been verified by anyone except for the authors.   Both of the founders of A-2 are now dead and no one is verifying their work.

In our calculation the very best milk is raw milk from cows grazed on green pastures and tested to assure that no bad bugs are present. This is the raw milk that makes people healthy, rebuilds human immune systems regardless of animal genetics. The FDA will not allow OPDC to explain what things raw milk improves medically.

Trust us….Grass fed, tested, Raw Milk is a highly effective medical food.

             See for details that cannot be explained here.

All the best,
OPDC Raw Milk Team


And here's from another email: Someone just told me   "As I understand it, Tom Cowan has somewhat reversed his opinion on the issue as he has learned more about it, backing off from the position he took in the introduction he wrote to "Devil in the Milk". So the jury is still very much out on this issue."


Prominent food researcher Dr. Thomas Cowan has been involved in thinking about the medicinal aspects of cow’s milk virtually his entire career.

His studies on the subject started in earnest when he read the book
The Milk of Human Kindness Is Not Pasteurized, by maverick physician, William Campbell Douglass, MD.

Cowan became convinced that a large part of the disease in this country is related to the way we handle, or rather mishandle, milk and milk products.

Raw and cultured dairy products from healthy grass-fed cows are one of the healthiest foods people have ever eaten. However, pasteurized milk products have caused more disease than perhaps any other substance people are generally in contact with.

However, he still felt that a piece of the puzzle was missing. Many of his patients, in spite of eating only the proper dairy products, still had illness and still seemed not to tolerate milk. Recently, he was asked to consider writing the foreword to a book called The Devil in the Milk, written by Dr. Keith Woodford, which was again an eye-opener for him.

All proteins are long chains of amino acids. Beta casein is a chain 229 amino acids in length. Cows who produce this protein in their milk with a proline at number 67 are called A2 cows, and are the older breeds of cows (e.g. Guernseys, Asian and African cows). But some 5,000 years ago, a mutation occurred in this proline amino acid, converting it to histidine. Cows that have this mutated beta casein are called A1 cows, and include breeds like Holstein.

Proline has a strong bond to a small protein called BCM 7, which helps keep it from getting into the milk, so that essentially no BCM 7 is found in the urine, blood or GI tract of old-fashioned A2 cows. On the other hand, histidine, the mutated protein, only weakly holds on to BCM 7, so it is liberated in the GI tract of animals and humans who drink A1 cow milk.

BCM 7 has been shown to cause neurological impairment in animals and people exposed to it, especially autistic and schizophrenic changes. BCM 7 interferes with the immune response, and injecting BCM 7 in animal models has been shown to provoke type 1 diabetes. Dr. Woodford’s book presents research showing a direct correlation between a population’s exposure to A1 cow’s milk and incidence of autoimmune disease, heart disease, type 1 diabetes, autism, and schizophrenia.

Simply switching breeds of cows could result in amazing health benefits.



By   Tom Valentine

It’s all about one ittybitty gene, and it’s driving me nuts

I know I should not let things get me so upset. After all, it isn’t as though there aren’t a myriad other irrational, illogical corrupt and asinine public positions taken in the health and food sector - so why should this one get to me more than the others?

Maybe it’s because I remember how much drinking milk meant to me as a growing boy. Or it is because I can envision millions upon millions of young children drinking their milk ( for better health) in school cafeterias everywhere. Whatever the reason, the fact that this story is being utterly ignored drives me to distraction. This is an issue that need not be controversial for decades before resolution -- like mercury in our mouths or trans-fatty acids found in billions of supermarket junk products. This issue can be resolved quickly, and it should be -- because we tell our kids to drink their milk every day

The issue is the genetic makeup of everyday cow’s milk. Whether that milk is A1 or A2 might make all the difference in the world to chronic disease rates of the future. Apparently it has made a difference in the amount of diabetes, heart disease, autism and other maladies for a long, long time.

We broke the sensational A-2 milk story a year ago in June and followed up with the breaking story of animal research verifying the controversial thesis that A1 milk is unhealthy in July 2003

Then the story suddenly stopped in its tracks, as if drinking milk isn’t a major factor in the health of young children. The two main protagonists behind this story in New Zealand died late in 2003. On top of that, the company here in America that purchased the rights to the A2 milk patents has had nothing to say … nothing!

This really, really bugs me. Even the people concerned with organic, raw milk are ignoring A2 milk. Why?

Because there are a lot of costly commercial changes that “all” the dairy industries must make when this genetic milk question gets the attention it deserves.

True Health is resurrecting this important milk controversy because serious health advocates are going to want raw, organic A2 milk -- especially for their children. We continue to be amazed that the major media in America has ignored this important story since it first erupted in the New Zealand and Australian press, and in scientific journals a few years ago

There is new information, thanks to the genes in the Guernsey breed of milk cows. Guernsey are naturally more genetically-capable of producing A2 dominant milk, and both the US and British Guernsey Breeding Associations have begun to sponsor more scientific studies to support the thesis as they genetically test their breeder bulls and herd in order to advertise this advantage

Be prepared to hear the naysayer chants from Holstein and other popular dairy breeds, as well as the modern dairy industry that brought you unsanitary, homogenized pasteurized and inferior products for decades.

Milk is a traditional staple food. It contains about 32 grams of protein per quart and 82% of that protein is casein. Casein is divided into four subclasses with beta-casein as the second most abundant. Scientists have determined 10 genetic characterizations for beta-casein with A1, A2, A3 and B found in virtually all common - Bos taurus - dairy cow populations. In a nutshell the thesis is : A1 milk is bad ; A2 milk is good.

Going back to the beginning, the story started in New Zealand, an island nation with dairy one its major exports. Back in 1991 Dr Bob Elliott, a paediatrician, noticed during clinical visits to the Pacific Islands that children of the islands did not have any Type 1 diabetes. He also noted that dairy cows were not part of the cultures of the islands.

( At True Health we are harkened back to the work of Dr Weston A Price in the 1930s, when he demonstrated conclusively that cultural differences in the diet clearly resulted in basic health differences. The Establishment ignored his work, but ‘what else is new?’ Of course, Dr Price did not have the modern science of genetics working for him )

Dr Elliott took his observations about the lack of diabetes dovetailing with the lack of cow’s milk to Dr Jeremy Hill, chief protein chemist for the old Dairy Board of New Zealand. Hill then suggested that the protein type might be to blame -- A1 beta casein as opposed to A2 beta casein

How Dr Hill knew such a possibility lurked has not been explained

Dr Elliott set out to prove A1 could be a disease cause. With the backing of the Dairy Board and the Child Health Research Foundation, he tested the idea on mice, feeding them either A1 or A2 protein.

None of the animals consuming A2 milk developed diabetes, many in the A1 group did. Elliott and the organizations knew they were on to something. The group filed for the first patents to test cows for A1 and A2 milk producers

However Dr Elliott committed an unpardonable sin in scientific circles … he gave his findings to the media before they were published in the peer-reviewed literature

Naturally the A1 diabetes connection was headlined for several days by the media Down Under, and the Dairy Board was stung by its own research. The eruption of controversy generated defensive dogma in the status quo and the work was happily dismissed by the world-wide industry / academic powers

Enter the late Dr Corrie McLachlan, a scientist whose passion had been heart disease. In 1990, he developed a cholesterol-free butter, but remained unconvinced that cholesterol was the main culprit in heart disease. When he looked at Elliott’s diabetes data for the first time in 1994, he exclaimed out loud “If I didn’t know better, I’d say I was looking at heart disease.”

He then spent about a year and a half collecting data on the two protein types of milk, comparing consumption amounts with disease figures.

One of the epidemiological observations noted by McLachlan, for example, pointed out that Finland has a very high incidence of heart disease and diabetes ; it also has a strong line of Ayrshire cows, which produce mostly A1 milk and very little A2

On the other hand, Iceland features dairy herds with high A2 production and little A1, giving the people a very high A2 consumption -- Iceland has virtually no heart disease nor diabetes!

McLachlan lodged his own patent for testing A2 milk, then asked the Dairy Board for more funding to continue research

Then confusion of the kind peculiar to peer-reviewed scientific circles reared its confounding head. Appearing much like today’s confused and agenda-driven science in other areas, such as into health implications of mercury amalgam fillings or microwave radiation and mobile phones, the verification process ran into snags and controversy

Interestingly, none of this news managed to stir the managed American media

The Dairy Board arranged for international studies to replicate Elliott’s initial diabetes work. The studies proved nothing. A Canadian animal study supported Elliott’s work ; Britain’s study did not, and Elliott’s own replication saw mice die of infections, spoiling any result. This is not at all unusual in scientific research. A summary of the fiasco suggests that mistakes in animal handling and changes in diets confused everything

Funding dried up without scientific resolutions. It was alleged that the Dairy Board had adopted an attitude. They wanted to simply leave well enough alone. The board denied it, and pointed to their filing of a new patent covering a test for identifying people susceptible to juvenile diabetes. ( No news has generated from this fact either.)

Ticky Fullerton, a capable Australian television interviewer summarized the case well :

“Just who would be susceptible to A1 milk was open to question. The hypothesis pointed to those with low immunity, but often this goes undetected. Nevertheless, a possible mechanism for how A1 milk might cause disease was proposed. Protein molecules of A1 and A2 milk are both chains of amino acids. But in the A1 molecule, one amino acid is different, a weak link. A2 researchers believed this causes the chain to break, creating a small piece called beta-casomorphin-7. And this piece is able to move through the gut wall in to the blood, triggering disease, That idea fuelled the hypothesis …”

Internationally, immunologists balked -- claiming the data was insufficient to prove the thesis. Stalling thus occurred on the research front.

Meanwhile, Dr McLachlan sold much of his valuable collection of rare books and borrowed from his family to keep his heart disease connection going.

“The data was too good,” he said. “I’m pretty good at research, and my guess was that the data was correct. I figured if I didn’t keep going, it would be buried forever and you wouldn’t see it”

Along came the late Howard Paterson, a dairyman with the kind of money to realize the potential in the face of strong, dogmatic opposition. Paterson noted not only the money-making potential, but he saw “a genuine moral imperative to do what is correct.” ( It would be nice if that moral imperative had more legs with today’s establishment.)

Despite “ a lot of Machiavellian stuff” Paterson, McLachlan and A2 Corporation managed to purchase half the patent protection from the old Dairy Board and combine it with new business parameters well enough to get on the stock market and cause a brief flurry.

This still wasn’t important enough news for the major media

The corporate plan is for farmers to pay $20 for a cow DNA test to determine A1 or A2, and the company anticipated a royalty on every glass of A2 milk sold henceforth. However both McLachlan and Paterson died late in 2003, and their driving forces seemed to die with them. A2 Corporation in New Zealand is no longer responding to emails and phone calls

Last year, Professor Julie Campbell, a noted Vascular Biologist at the University of Queensland, Australia used rabbits as test animals and found “highly significant” results. The animals fed A1 developed much higher serum cholesterol levels than those fed A2

On television Dr Campbell said :

“we found that the A1 made the juvenile fatty streaks, the ones you get in children, much worse. So it may be important the type of milk that children drink ; whether it has A1 or A2 casein. However, by the time you are an adult, it’s not going to affect you whether you drink one or the other, but the damage may have been done in childhood.”

Her opinion on adult affects was merely an opinion. Whether adults are affected less than children is not supported by any science at this time.

Dr Campbell’s published study should have been major news worldwide. Of all the media, only True Health told the story -- in our July-August 2003 issue. The following additional information was gleaned from that story:

The particular genetic version of A1 is found in the majority of western civilization’s cows with Holstein and Ayrshire breeds producing 63% and 67% A1 respectively, leaving 35% and 33% of the casein the A2 variety.

The differences between A1 and A2 protein is very slight, showing up in a single amino acid in the long chain. Genetic research has determined that the only difference is on condon 67 where A2 has the amino acid proline and A1 has the amino acid histadine. This single amino-acid sequence differential appears to be significant in living mammal biology

Researchers in Australia explained the possible mechanism whereby A1 is detrimental while A2 is beneficial.

“What are the possible mechanisms by which the different casein variants affect the development of atherosclerosis? Firstly, there is the effect of beta-casein A2 on lowering serum cholesterol. Secondly, beta-casein A1 and not A2, releases beta-casomorphin-7, which is thought to be involved in the oxidation of LDL cholesterol through a peroxides-dependent process. Beta-casomorphins have been detected in the plasma of newborn calves and in the small intestines of humans after cow milk consumption …”

In technical language the paper further explains that an enzyme called elastase releases the carboxyl terminus of beta-casomorphin-7 between the 66 and 67 ( histadine) positions on the chain of amino acids as they are found on the A1 protein. Elastase is unable to cleave the bond at the same position on the A2 protein, which means the beta-Casomorphin-7 cannot be released. The paper then references studies showing how the beta-Casomorphin-7 is implicated in arterial lesions and LDL oxidation.

Additionally the researchers found during the study that A1 appears to enhance opportunity for chronic inflammation in arteries, which is a known risk factor for heart disease.

Epidemiological studies conducted by Dr McLachlan were cited in the paper. He had found a correlation between A1 milk consumption and ischemic heart disease in West Germany to be three times greater that the correlation between smoking and ischemic heart disease

Conversely, the populations of Masai and Samburu peoples of Africa, whose diet is chiefly milk and meat from Zebu cattle, are virtually free of ischemic heart disease. The African Zebu variety - Bos indicus - produce almost entirely A2 milk.

The study authors concluded :

“These measures ( removing A1 producers ) may thus contribute to improved human health by reducing a risk factor that contributes to ischemic heart disease, the leading cause of premature death in the developed world today”

Now that is news!

Meanwhile, a similar trial using mice instead of rabbits, showed the opposite effect -- A2-fed animals seemed to show slightly larger areas of lesions. So, while mice were significantly affected in a diabetes trial, in this heart disease trial researchers found an opposite situation

However it is know that mice do not naturally get the heart disease, and in the trials they were fed an extremely high-fat diet, which may have masked the protein results. Nevertheless, the test was hailed by fearful status quo hopefuls as a strike against the A2 thesis ( with the entire controversy still managing to avoid media coverage)

The good news is : the Guernsey Cattle Federation sees a tremendous breeding opportunity worldwide, especially in the export of semen to breeders. True Health recently contacted both the English Guernsey Cattle Society and the American Guernsey association

Digby Gribble of the English group said a study is planned which will test the hypothesis that A1 milk may contribute to Autism while A2 milk does not. This study is to be under the guidance of Professor Brostoff of King’s College Hospital, London. Gribble told us :

He proposes to monitor proteins excreted in the urine of 20 Autistic children. These children will be on casein-free diets already as this is the normal practice on diagnosis of Autism. They will then be given A2 Guernsey milk from a herd that have all been tested and any cows not A2xA2 will have been removed.

“The proteins in the urine will be measured again and if, as we expect, there are no side effects, then the trial will be repeated with “ordinary“ milk which will be a mix of A1 and A2. If the theory that A1 is the trigger then this should show in the urine and in the behaviour of the children”

Gribble explained that the autism project was selected because results will be determined in relatively short order, whereas diabetes and heart disease require long-term verification

The Guernsey breed has been tested in the US and the UK to produce milk that is more than 90% A2, the Breed Societies are testing all bulls used in Artificial Insemination and are making the beta-casein status known to breeders

“In the UK we will no longer use bulls that have tested A1xA1 in artificial insemination and will move to only A2xA2 as soon as we are able. At this time, only the New Zealand Dairy board have tested and published the test results for all of their bulls.”

Seth Johnson of the American Guernsey Association reported :

“The A2 issue was the topic of much discussion at the annual convention in July, and we have received many requests about A2 as it finally seems not be registering on the radar of the North Americans. Our research and education foundation, the Guernsey Foundation, approved funding for testing of cows in various regions of the US in the next few months.”

He added that the association expects to get an accurate picture of where the US Guernsey population stands regarding A2 genetics within a short time. He said he hopes the US Guernsey herds will be able to provide an A2 milk product as the market for it opens up.

Still no major media coverage



Recent Photos

Recent Videos

854 views - 0 comments