Four years ago, I wrote an article and filmed a video about the differences between A1 and A2 milk.  The A1 versus A2 factor refers to the different type of casein in raw milk from various breeds of cows.
Note that sheep milk, goat milk, and camel milk are all A2 milk regardless of breed.
Much of the hubbub regarding A1 versus A2 milk at that time and in the ensuing years resulted from an article written by Dr. Tom Cowan based on the book The Devil in the Milk which claims that cows made a genetic split about 5,000 years ago which resulted in Holsteins and Friesians (black and white cows) becoming favored for domestication because of calmness and other traits.
These cows became the A1 dominant cows of today which supposedly produce milk which acts like an opiate when consumed and which epidemiological studies have implicated in heart disease, Type 1 diabetes, autism and schizophrenia.
The book also claims that old fashioned breeds of cows produce A2 milk that is far healthier and that genetic testing is required to determine if a cow has A1 or A2 genetics.
As I have read more about this issue, it seems that in reality, we have no way of knowing whether any of this is true or not. There is no other research that confirms this historical split. If this genetic divergence truly occurred 5,000 years ago and A1 milk  is one of the sources of heart disease and makes autism worse, why doesn’t this match up with what other researchers are finding?
Unnatural feeding of dairy cows, confinement and pasteurization/homogenization that got started early in the last century are far more likely culprits for any health issues associated with milk consumption, not cow genetics.
If fact, in the comments section of that post I wrote four years ago, Mark McAfee, Founder of Organic Pastures Dairy in California, said the following:
Sarah,
I agree with much of what you have shared….but let me help out by filling in the blanks a little. I am very close to this A-2 subject matter and can help clear the air.
Dr. Cowan has privately apologized to me for writing the forward to The Devil in the Milk. He said that if he knew then what he knows now he would not have said what he wrote.
The A-2 story is far from conclusive. Instead of “The Devil is in the Milk”….the better statement is.. “The Real Devil is in the CAFO Grain Feeding of the Cows and Processing of the Milk”.
Keep up the great teaching and nutritional work!!
Most kind regards,
Mark McAfee
Founder Organic Pastures Dairy Company
Fresno CA
I recently emailed Mark to see if he had any additional information on the A1 and A2 milk issue, and he responded by saying that he would be attending the upcoming International Milk Genomics conference in Aarhus, Denmark, where A2 will be discussed in depth. Â But, at the present time, his opinion is the same – that the jury is still out on the A1 versus A2 milk issue and whether cow genetics is of any importance whatsoever.
Should You Care About A1 and A2 Milk?
While it is clear that cow genetics plays a role in how a herd responds to environmental conditions and can be used to select the most appropriate breed for a given locale, it is far less certain whether cow genetics plays a role in production of the best milk from a nutritional point of view.
The most important thing for the consumer at the present time is to ensure that the farm they purchase their milk from has a healthy herd which grazes on well kept, unsprayed green pasture. In addition, visual examination of the milk to assess the size and color of the creamline indicating the presence of fat soluble vitamins and co-factors is most important.
Organic Pastures Dairy in California seems to be of the same mindset. Â The FAQ on the OP website says the following:
We do not test for A1/A2 genetics. It is our opinion that raw, non-homogenized milk, from organic cows that graze on pasture makes the most nutritious milk. We have 10 different breeds that make our milk delicious and nutritious. We believe the genetic diversity of our cows adds to the overall nutritional diversity of their milk.
Well said.
Sarah, The Healthy Home Economist
More Information
I had been “lactose intolerant” for many years. I’ve tried raw mild from both Holsteins and Jerseys and tolerate both equally well. I do have to say though that the milk from the Jerseys is far superior in flavor and cream content. Maybe it’s just our local cows, but around here you can’t beat Jersey milk!
I really hope you’ll check in with Mark when he gets back from the conference – or better yet – review independent reviews of the conference – and report back!
Thanks, Katie
Our family has had allergies to dairy in small children and one adult. There is definately a difference between the milk from A1 or A2 cows from the same organic dairy farm. A1 milk caused more issues even if it was raw, unpasteurized milk.
Thank you for this! One farm I know uses the fact that they test their cows for A1/A2 as an excuse to jack up the price of their milk and rip off their customers. They go on and on about it like the A1/A2 thing is fact when now I know its not.
I know this was a comment made several years ago, but I can’t help but reply. My farm is a 100% grass-fed raw milk dairy with 15 dairy cows. We have been in business for 5 years. We sell our a1/a2 milk for $10/gallon and our A2 milk for $14/gallon. You might say I’m “ripping off” my customers. But if you looked at my financial records, you would see we are barely making a profit–and that is with my 6 kids working for FREE every day for at least 2 hour a piece. (Over the course of 5 years in business, we have incurred over $65,000 in debt just in operating expenses, after depleting our retirement accounts and coming to our farm with a significant amount in savings.) People have NO IDEA how expensive it is to start up a farm and to continue to cover ongoing expenses. Our feed bill is through the roof. My electricity bill was $1200 last month with all of our freezers, fridges, bulk tanks, water heaters, etc. How do I justify charging more for my A2 milk than I charge for my A1 milk? #1, clients are willing to pay more for it because they see a difference in their own health or the health of their own children. I give them a choice and they choose the A2 milk for THEMSELVES through their own personal experience. I have a second bulk tank that cost me $3000 so that I can separate the milk. And I have to milk all of my A2 cows first, then adjust the equipment, in order to separate the two kinds. Those who don’t have bulk tanks have to go to extra measures to cool their milk separately too. The truth is, I NEED to be charging $14/gallon for ALL of my milk to actually make it financially sustainable to continue to produce high quality, 100% grass-fed raw milk. But my hope is that by gradually breeding toward a full herd of A2 cows (right now 1/3 of my herd is A2A2), I can shift my client base up to the higher prices in a gradual way. If I just raised my prices on all of my milk to $14/gallon, I could loose too many clients at one time. But the reality is, I would be out of business if I hadn’t started charging $14/gallon for the A2 milk a few months ago. Our profits were simply too slim. But I continue to produce milk because I believe it is important. Before anyone accuses a small sustainable farm of “ripping off” people, they might want to ask the farmer if they are above the poverty line yet selling their products, or how many hours they have to work off the farm to pay off the debt the farm continues to incur even after accounting for any sales income.
I believe that all goat’s milk is A2/A2, and that might be part of the reason why many people can tolerate goat’s milk much more than cow’s milk. We have dairy goats and we have an old breed of cows–Irish Dexter. Both graze in untreated pastures–as close to organic as possible without being certified. We have some A2/A2 cows that we hope to milk someday so we can see how we react to their milk. In the meantime we use our raw, unpasturized goat’s milk to make kefir, cheese, and yogurt. If yogurt cultures for 24 hours, lactose is removed. Thanks!
Australia had some major controversy over this, some are pretty settled on this issue
We have been consuming Organic Pastures milk for more than a decade now. I have always had some digestive issues with drinking their milk, although it is easier for me than pasteurized milk, by far. We have recently been able to get raw milk from another source and they can offer us A2 milk on a limited basis. I can drink more of the A2 milk from this source than I can their A1 milk – it comes from the same farm, but from different cows, so I don’t think there are other factors that could explain the difference in my ability to digest it. The A2 milk is easier on my digestive system than any other kind of raw milk that I’ve tried. So from my personal experience, I do find that there seems to be something in this theory, even if it hasn’t been scientifically proven.
While I would agree that the research is not complete, we’ve had plenty of anecdotal evidence from customers of our farm that lead me to believe that there is something to it. Numerous people have commented to us how they’ve had trouble with raw milk form other small farms, but they can digest ours just fine, as our cows are all certified A2. Large dairies, such as Mark McAfee’s, also have somewhat of a disincentive to test for and acknowledge that there is a difference, as they would have to replace possibly large portions of their herd at considerable time and expense.
very interesting, thanks hon
Chris Kresser talked about this recently as well, and mentioned some of the flaws of the A1/A2 studies:
http://chriskresser.com/the-healthy-skeptic-podcast-episode-5
“The original research that was done on this issue was performed in vitro, meaning in a petri dish, using a limited set of enzymes that the researchers thought would be involved in the digestion of casein in the gut. Now, the idea is that none of our enzymes can actually break down that BCM7, and this would allow it to pass into the bloodstream, especially in individuals with a leaky gut.
But this is a flawed idea, because we don’t actually know what all of the enzymes in the gut are or what their actions are, and it turns out that we’ve learned recently that there’s an enzyme in the gut called DPD-4, which is really good at cleaving the peptide bonds next to proline and fully breaking down the BCM7 peptide.
So Mat pointed out that there’s no study, at least that we’ve been able to find, where they actually found BCM7 in the bloodstream of a human being. And, of course, it has to get into the bloodstream to cause oxidative damage and disrupt brain and immune function.”