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Peter Bongiorno ND, LAc
Peter Bongiorno ND, LAc

Got to Drink Milk? Learn Your A1’s and A2’s

What you need to know about the milk you drink

By Peter Bongiorno ND, LAc with Pina LoGiudice ND, LAc

A1 or A2 cow's milk?

Cow’s milk is a staple food in many homes. Unfortunately cow’s milk itself may be a silent, but potent factor in a number of illnesses, including cardiovascular disease, diabetes, inflammatory issues, gastrointestinal health, and mood disorders. It may also be a strong contributor to infant and children’s health problems. Emerging research suggests the type of cow’s milk you drink may be a part of the issue.

“But I Grew Up Drinking Milk, and I Am Just Fine”

On average in the United States, each person drinks about 20 gallons of milk a year. While this is a good deal of milk, this has declined since the ‘70’s, and is not as much as in countries like Finland, the Netherlands and India, where consumption is around 30% higher. It should be noted that children generally drink a higher proportion of milk for their body weight.

Most of us grew up on the idea that milk is a healthy source of protein, vitamin D, and calcium. As naturopathic doctors with a combined 20 years of experience, we generally see more problems in patients who consume milk and dairy products. The most obvious associations we have seen revolve around digestive problems such as irritable bowel syndrome, colitis, Crohn’s Disease, and of course, lactose intolerance. We also see association with skin issues such as acne, sinusitis, inflammatory and autoimmune diseases (like Hashimoto’s thyroiditis, lupus, multiple sclerosis, and sarcoidosis), as well as neurologic and mood issues such as depression and autism. While some children may react to milk overtly, many have lower grade issues such as low grade digestive problems, skin issues, allergies, mood problems, and more.

One author of this article (PB) stopped regularly drinking milk in his 20’s to find all ‘environmental allergies’ and frequent colds and flus to reduce to virtually none. This resulted in his not taking a single antibiotic in the last 25 years. The second author (PL) drastically reduced her milk consumption, along with gluten, to find significant benefit to prior digestive tract issues.

Research Suggests Milk May Not Be So Healthy

While the conventional medical community has not, as a whole, acknowledged the milk correlation to health problems, some more progressive physician groups are starting to connect the milk dots. For example, the Physicians Committee for Responsible Medicine (PCRM) cites abundant growing research linking breast and prostate cancer, obesity, diabetes, and cardiovascular disease with milk intake.

PCRM also warns that children’s health is also affected: childhood obesity, food allergies, pediatric colic, and infant iron deficiency are some of the conditions likely spurred on by milk consumption (1). Other studies also show milk ingestion linked to mood disorders like schizophrenia, autism, as well type I diabetes (2,3,4) and even Sudden Infant Death Syndrome (5). PCRM also accurately notes that for bone health, dairy products are not necessary to keep levels calcium and vitamin D. Bone health and that these are easily achieved by eating healthy foods.

A1 versus A2 Milk?

is this an A1 or A2 cow?

Is this an A1 or A2 cow?

It seems that all milks may not be the same: It is possible that the risks of drinking milk may depend on the version of milk you buy.

While not well-known, even in most nutrition and natural health circles, the fact is there are genetically different cows out there—A1 cows and A2 cows. All cows used to be A2 cows until a naturally-occurring genetic mutation in European cows changed the genetics of milk-producing cow herds. Easily distinguished using a simple DNA test, it is established that now, A1 cows produce the majority of the milk we drink.

The main proteins in milk are whey and casein. Casein is the most abundant overall, and the genetic variations of A1 and A2 refer to a specific type of casein known as beta-casein. Beta-caseins can have helpful effects in the body. For example, the beta-caseins from breast milk help the newborn immune and gastrointestinal systems develop properly.

But, drinking A1 milk may not be so helpful. When you drink milk from an A1 cow, your body breaks it down to produce high levels of a molecule that is not healthy. This is a bioactive opioid peptide and morphine-related compound called beta casomorphin-7 (BCM7). While A2 milk will also cause some of this morphine molecule to be produced, it is negligible compared to A1 milk (6).

BCM7 is a very active molecule in our body, and once in our blood stream, this opioid will oxidize cholesterol at a high rate, which may be one reason for the link to heart disease. Animal studies have singled out BCM7 to create inflammatory reactions in the small intestines (7). It also changes hormonal function, as well as affects the nervous and immune system (8). BCM7 will cause brain fog, poor thinking, as well as problems with sleep (9). These neurologic issues may also be a factor in the concerns with schizophrenia and autism.

Ischemic heart disease is the most common cause of death in the majority of countries. A study out of New Zealand looking at 20 affluent countries clearly show higher rates of death from a type of heart disease called ischemic heart disease in A1 drinkers, while A2 drinkers show lower cardiovascular problems and type I diabetes (10, 11, 12).

Does Everyone Think A1 Milk Is A Problem?

Right now, besides more enlightened physicians groups like PCRM, most conventional medical people are not concerned. Some small studies do contradict the larger body epidemiologic research about A1 milk. One study suggested there were no changes in cholesterol regardless of the milk that ingested (13). It should be noted though that this was a small short-term study, and cholesterol by itself is not be the best indicator of long term heart disease risk.

The European Food Safety Authority in 2009 conducted their own review of the literature and suggested that there is no benefit of A2 milk over it’s more common A1 counterpart. Even more, it concluded that a cause and effect relationship is not established between the dietary intake of A2 milk and disease. As a result, they decided a more formal investigation was not needed (14).

While it is true there are not enough studies to create a cause and effect relationship, the epidemiologic and research studies are still quite compelling, and in our opinion, should not be ignored. The majority of the research we have read suggests this A1/A2 should be taken seriously and studied further. We have also anecdotally heard from a few parents who suggest that switching to A2 milk helped resolved symptoms of mild autism in their children, while a few adults swore their ‘lactose intolerance’ is not a problem with A2 milk.

What About Grass Fed Cows and Organic Milk?

I know many of you reading this are thinking: “Well, I buy organic, so that is the best.” Well, unfortunately, most organic milks on the shelves are A1 milk too. So while milk that is labeled organic and grass may have less pesticides and antibiotics, it doesn’t fix the baso casomorphin-7 problem.

Milk Challenge To Try

If you suspect milk may be a contributing factor to a health concern, try the following steps (note: if you have any life-threatening inflammatory/allergic issues, please work with your doctor on this):

1 - avoid all milk and dairy products for six weeks, to give any inflammatory processes a chance to calm.

2 – if your symptoms improve 90-100%, try A2 milk for two weeks, and see if your symptoms return. If not, it may possibly be a sensitivity to the BCM7 in A1 milk.

3 - If your symptoms do return when taking the A2 milk, it might be worth avoiding both A1 and A2 milk, and switching to alternative milks (such as almond, oat or rice milks). Many people who react to both A1 and A2 milk may be sensitive to other aspects of casein, whey and lactose, which will still promote inflammatory issues. Also, goat and sheep’s milk is not known to contain BCM7, and may also be a less inflammatory choice for some people.

4 - If your symptoms do not improve when all milk is avoided for 6 weeks, then it may not simply a milk issue, and you may need to try eliminating other foods, or start working with a holistic practitioner to further figure things out.

Where Do I Find A2 Milk?

To find A2 milk, look for a dairy farm that uses only A2 cows. Asian and African cows are known to be mostly A2, whereas European and American cows are mostly A1. Two breed of A2 cows in America are the Jersey and Guernsey cows.

Final Note: Leaky Gut, Homogenization and Pasteurization

Please also note that some people with gut issues and leaky gut syndrome may also be more prone to sensitivities to milk and a host of sensitivities to other foods. Additionally, if at all possible, we would also recommend trying milk that is not homogenized, for this destroys the nutrient benefits of milk without conferring any more safety. We also recommend drinking a milk that is pasteurized the lowest possible temperature. The issues of leaky gut, homogenization and pasteurization will be discussed on future blogs.

Naturopathic Conclusion

As of right now, research is mounting which concerns us about the ingestion of A1 milk. While we suspect many people may be sensitive to a number of proteins in cow milk, it is possible that A2 milk many provide an alternative that might avoid the myriad of problems associated with the everyday milk in our supermarkets. More research is needed, but for those who have health challenges, this issue may be worth exploring.

Peter Bongiorno and Pina Logiudice

About the authors:

Husband and wife team, Drs. Peter Bongiorno and Pina LoGiudice co-direct New York-based InnerSource Natural Health and Acupuncture, with practices in New York City and Huntington (Long Island), New York. They can be reached through . Their 5 year-old daughter Sophia gets quickly stuffed up when eating dairy products.

Peter Bongiorno and Pina Logiudice

About the authors:


1 - The Physicians Committee for Responsible Medicine (PCRM) "Health Concerns About Dairy Products," available at… (accessed 02-15-2014)

2 - Birgisdottir BE, Hill JP, Thorsson AV, Thorsdottir I. Ann Nutr Metab.2006; 50(3):177-83.

3 - Harris D P, Hill JP, Bibby NJ, Wasmuth HE. Type I (insulin-dependent) diabetes mellitus and cow milk: casein variant consumption. Lower consumption of cow milk protein A1 beta-casein at 2 years of age, rather than consumption among 11- to 14-year-old adolescents, may explain the lower rate of type 1 diabetes in Iceland than in Scandinavia. Diabetologia. 1999;42:292–6.

4 - Cade R, Privette M, Fregly M, Rowland N, Sun Z, Zele V, et al. Autism and schizophrenia: Intestinal disorders. Nutr Neurosci. 2000;3:57–72.

5 - Sodhi M, Mukesh M, Kataria RS, Mishra BP, Joshii BK.Milk proteins and human health: A1/A2 milk hypothesis. Indian J Endocrinol Metab. 2012;16(5):856.

6 - Jinsmaa Y, Yoshikawa M. Enzymatic release of neocasomorphin and beta-casomorphin from bovine beta-casein. Peptides. 1999; 20:957-962.

7 - Trompette A, Claustre J, Caillon F, Jourdan G, Chayvialle JA, Plaisancié P. Milk bioactive peptides and beta-casomorphins induce mucus release in rat jejunum. J Nutr. 2003;133(11):3499-503.

8 - Bell SJ, Grochoski GT, Clarke AJ. Health implications of milk containing beta-casein with the A2 genetic variant. Crit Rev Food Sci Nutr. 2006;46(1):93-100.

9 - Shattock P, Whiteley P. Biochemical aspects in autism spectrum disorders: updating the opioid-excess theory and presenting new opportunities for biomedical intervention. Expert Opin Ther Targets. 2002;6(2):175-83

10 - Laugesen M, Elliott R. Ischaemic heart disease, Type 1 diabetes, and cow milk A1 beta-casein. N Z Med J. 2003;116(1168):U295.

11 - Tailford KA, Berry CL, Thomas AC, Campbell JH. A casein variant in cow's milk is atherogenic. Atherosclerosis. 2003;170:13–19

12 - McLachlan CN. β-Casein A1, ischaemic heart disease mortality and other illnesses Med. Hypotheses, 56 (2001), pp. 262–272

13 - Venn BJ, Skeaff CM, Brown R, Mann JI, Green TJ. A comparison of the effects of A1 and A2 beta-casein protein variants on blood cholesterol concentrations in New Zealand adults. Atherosclerosis. 2006 Sep;188(1):175-8. Epub 2005 Nov 18.

14 - European Food Safety Authority.Review of the potential health impact of β-casomorphins and related peptides. 03 February 2009. EFSA Journal.

About the Author
Peter Bongiorno ND, LAc

Peter Bongiorno is a naturopathic doctor and the author of Healing Depression: Integrated Naturopathic and Conventional Treatments.

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