A1 Beta Casein: The Devil in Your Milk

February 4th, 2010

Although milk is one of the most common foods in the modern diet, pasteurization and modern dairy farming practices pose a number of concerns. In addition, many people are unable to properly digest dairy and it’s also one of the most common sources of food sensitivities which can cause a number of seemingly unrelated symptoms. As if this isn’t enough to worry about, there’s unfortunately another important and potentially harmful aspect of milk to consider.

Two varieties of proteins exist in milk. The most prominent is casein which represents 80% of the protein in milk, and the other, which is much more widely recognized, is whey. The digestion of a specific type of casein has been found to produce an opioid byproduct that can be very problematic for humans as well as animals. There’s strong evidence that links this casein and its opioid derivative with heart disease, mental disorders such as autism and schizophrenia, type 1 diabetes, and a number of other autoimmune disorders. Fortunately, there are simple ways to avoid these risks.

A1 Beta Casein and its Troublesome Opioid Derivative

The problematic type of casein protein found in milk is called A1 beta casein. It’s known to be the result of a genetic mutation in cattle that’s believed to have occurred about 8,000 years ago in Europe. As such, only certain breeds of cattle produce milk that contains A1 beta casein.

A1 beta casein is a string of 209 amino acids that very closely resembles another type of milk protein called A2 beta casein. The only difference between the A1 and A2 beta caseins is just a single amino acid. A1 beta casein contains the amino acid histidine in position 67 instead of the amino acid proline that exists in this position in A2 beta casein. Although this sounds like a minor difference, it’s actually quite significant because the bond between histidine and its adjacent amino acid in A1 beta casein is much weaker and much more easily broken than the bonding of proline in A2 beta casein.

Because of the weak bonding of histidine, A1 beta casein is commonly broken down into a peptide of 7 amino acids called beta casomorphin 7 (BCM7) during digestion. Although it’s also possible for BCM7 to be produced from A2 beta casein, it’s much less likely, and if it were to happen, it would be in much smaller amounts.1 BCM7 is problematic because it’s an opioid which makes it the equivalent of a narcotic with morphine like effects. It’s also an oxidant that’s particularly known for damaging low density lipoproteins (LDL). Because the bonds between the 7 amino acids that constitute BCM7 are very strong, it’s resistant to further breakdown which therefore increases its potential to cause problems.

When BCM7 Enters the Bloodstream

Many of the problems relating to BCM7 can only occur if it’s absorbed through the stomach or intestines and into the bloodstream. However, BCM7 is too large to be absorbed through a healthy intestinal lining which means that health issues relating to A1 beta casein are often associated with compromised digestive health or conditions such as celiac disease and stomach ulcers. People who suffer from any of these conditions are likely to have increased intestinal permeability which means that BCM7 will enter the bloodstream more easily. Because babies naturally have increased intestinal permeability for improved nutrient absorption, they’re at risk as well.

Once in the bloodstream, BCM7 can readily pass through the blood brain barrier into the brain where it can bind to opioid receptors and cause symptoms of autism and schizophrenia. This has been supported by research that found rats to exhibit behavioral tendencies similar to those of autism and schizophrenia after being injected with BCM7. The association between these effects and BCM7 was further supported by the ability to reverse the behavioral changes with the opioid antagonist naloxone.2

In addition, it’s been known for a long time that opioids have an effect on immune function which is a possible reason why A1 beta casein and BCM7 are so closely associated with autoimmune disorders.

A1 Beta Casein and Heart Disease

Based on misconceptions about cholesterol, most people are likely to blame the ironically nutritious saturated fat content of milk for any association that might exist between it and heart disease. However, A1 beta casein has been shown to be a much more likely contributor.

Although epidemiological evidence doesn’t prove anything, it’s certainly important to consider, and the evidence linking A1 beta casein to heart disease is very strong. In 2001, Dr. Corran McLachlan analyzed the number of deaths resulting from heart disease in 17 different affluent countries for the years 1985 and 1990 and for people aged between 35 and 69.3 This data was compared to each country’s consumption of A1 and A2 beta casein proteins as well as the consumption of dairy protein in general. The results showed a weak correlation between heart disease and dairy protein, an even weaker correlation with A2 beta casein, but a very strong correlation between A1 beta casein and heart disease. This last correlation was statistically significant with the possibility of it occurring by chance being less than one in a thousand.

In 2003, Dr. Murray Laugesen and Professor Bob Elliot conducted a similar study in which they carefully chose 20 affluent countries to minimize the influence of poverty and lack of medical care and assessed the number of deaths caused by heart disease for 4 different years.4 Once again, the correlation between A1 beta casein consumption and mortality from heart disease was very high with the possibility of the association occurring by chance being less than one in a thousand. They also evaluated data for 77 other types of food and 110 other measures of nutritional intakes to identify any additional correlations with heart disease. Although a few were identified, none of them were nearly as strong as the correlation between heart disease and A1 beta casein.

A closer look at the epidemiological evidence reveals more interesting information. People from Iceland and Finland are ethnically similar and also follow similar diets. Finland has one of the highest levels of heart disease in the world while the levels for Iceland are much lower. Iceland has 60% as much heart disease as Finland, and Iceland also consumes 60% of the A1 beta casein that Finland consumes. A similar scenario exists in the UK. The amount of heart disease on the island of Guernsey is about a third of that for the rest of the UK. Both Iceland and the island of Guernsey use breeds of cattle that produce much less A1 beta casein. Also interesting is that the Masai and Samburu tribes in Africa consume large amounts of milk but have very little heart disease. The milk they drink happens to be from cattle that don’t produce A1 beta casein.

Additional research that may explain how A1 beta casein can contribute to the development of heart disease found that BCM7 oxidizes low density lipoproteins (LDL) which transport cholesterol from the liver to body tissue.5 This is important because oxidized LDL is believed to increase the risk of heart disease due to increased inflammation of the artery lining and a subsequent buildup of plaque.

Evidence supporting the link between A1 beta casein and heart disease comes from animal research as well. In 2003, a team of researchers in Australia found that A1 beta casein caused larger fatty plaque lesions in the arteries of rabbits than A2 beta casein.6 The researchers concluded that A2 beta casein provided a mild level of protection against atherosclerosis while A1 beta casein most definitely contributed to its development.

A1 Beta Casein and Type 1 Diabetes

The evidence linking A1 beta casein and type 1 diabetes is very convincing as well. In 1999, Bob Elliot and Jeremy Hill conducted an epidemiological study on the incidence of type I diabetes in children aged 0 to 14 in 10 different countries.7 Although overall milk protein consumption didn’t correlate with the incidence of diabetes, the consumption of A1 beta casein certainly did. The study mentioned earlier that Elliot did with Dr. Murray Laugesen confirmed this correlation as well.4

This epidemiological evidence is further supported by research done on animals. In 1997, Bob Elliot and Jeremy Hill conducted a study on mice that were susceptible to diabetes and found that 47% of the mice fed A1 beta casein developed diabetes compared to none of the mice fed A2 beta casein.8 Another similar study, named the Food and Diabetes (FAD) trial, was conducted in 2002, but the conclusion of this study opposes the idea that A1 beta casein poses any health risks.9 However, this conclusion appears to be very much based on the industry bias of the authors and some technical flaws in the research such as some of the A2 beta casein feed being contaminated with A1. Despite this, certain aspects of the research still showed a statistically significant correlation between A1 beta casein and type 1 diabetes.

Type 1 diabetes is often classified as an autoimmune disease and can be caused by the immune system attacking the insulin producing cells of the pancreas. In 1999, scientists in Germany found a strong correlation between type 1 diabetics and high levels of antibodies for A1 beta casein.10 It’s believed that these antibodies are actually based on the amino acid sequence of the problematic opioid BCM7 that’s derived from A1 beta casein. Because this sequence has similarities to the protein structures of insulin producing cells in the pancreas, the antibodies attacking pancreas cells along with BCM7 peptides. This is similar to the autoimmune response that often results from sensitivity to gluten.

A1 Beta Casein and Mental Disorders

Because BCM7 is an opioid, it shouldn’t be surprising that there is also convincing evidence linking A1 beta casein to mental disorders such as autism and schizophrenia. The prevalence of autism in particular and its related disorders seems to be increasing at a shocking rate, and although there’s a lot of variations in the estimations of what the incidence actually is, some suggest it’s as high as 1 in 100 or even higher.11

The symptoms of autism and schizophrenia can be remarkably similar to those caused by opioids. The BCM7 derived from A1 beta casein and the gluteomorphin derived from gluten are both opiods that can contribute to these symptoms. This is why so many autistic children have experienced dramatic improvements from following a gluten free and casein free diet. The connection between autism and opioids is nothing new. It was first suggested in 1979 by a scientist named Jaak Panksepp.12

In 2000, a team of researchers led by Robert Cade reviewed the existing evidence associating casein and gluten opioids with autism and schizophrenia. They also evaluated new data of their own which was collected from 150 autistic children, 120 schizophrenic adults, 43 normal children, and 76 normal adults.13 The autistic children and schizophrenic adults consistently showed abnormally high excretion levels of casomorphin and gluteomorphin opioid peptides derived from beta casein and gluten. They were also found to have greatly enhanced antibodies to casein and gluten.

Of the 70 autistic children put on a gluten free and casein free diet, 81% improved significantly within three months, and more than a third of those who didn’t improve where still excreting high levels of opioid peptides suggesting that they weren’t following the diet. Although the improvement rate for the schizophrenic adults was only 40%, it’s believed that many of them didn’t stick with the diet long enough to allow of the existing BCM7 molecules to be eliminated from the brain which could potentially take longer than a year. While the results from a gluten free and casein free diet are often anecdotal, the amazing improvements that many people have experienced should certainly not be ignored.

The effects of A1 beta casein on autism and schizophrenia are further supported by animal research. In 1999, Zhongjie Sun and Robert Cade injected the BCM7 opioid derivative of A1 beta casein into rats to determine if it entered the brain.14 They found that it had attached to a number of different areas of the brain that had been previously shown to be associated with autism or schizophrenia. As a result, it was concluded that BCM7 could pass through the blood brain barrier and affect brain regions similar to those affected by autism and schizophrenia.

The same year, they conducted a similar trial and found that the rats injected with BCM7 exhibited several notable symptoms that are characteristic of autism and schizophrenia such as increased hostility, decreased sensitivity to pain, and lack of response to an auditory stimulus.2 In 2003, Sun and Cade continued their research and found that the gluteomorphin opioid that’s derived from gluten affects only 3 regions of the brain while the BCM7 opioid derived from A1 beta casein affects 45 regions.15 Not only does this show that BCM7 gains access to the brain much more easily, but also that it’s much more of a factor in the development of autism and schizophrenia.

Allergic Reactions and Other Diseases

The association between A1 beta casein and the serious disorders presented thus far are those which are supported by the most convincing evidence. However, this doesn’t mean that A1 beta casein isn’t associated with other health issues as well.

Because A1 beta casein has been shown to invoke immune activity, it can cause a wide variety of symptoms associated with food sensitivities and allergies. In fact, many people who once believed they were lactose intolerant or sensitive to casein have realized that they can drink milk without issue as long as it doesn’t contain A1 beta casein. There’s also reason to believe that A1 beta casein can contribute to the development of other diseases and autoimmune disorders such as multiple sclerosis, Parkinson’s disease, and sudden infant death syndrome, but more research is needed to support these claims.

Opposition from the Dairy Industry

The A1 beta casein issue seems to have received the most attention in New Zealand. Fonterra, the largest dairy company in New Zealand, originally showed concern about A1 beta casein but has since embraced the position that it poses no risk to human health and is a non issue. However, in 2001, the New Zealand Dairy Board, which later became Fonterra, filed a patent application acknowledging the association between A1 beta casein and neurological disorders.16 It’s also worth noting that some of the research described earlier which strongly implicates A1 beta casein as a possible cause of type 1 diabetes was conducted in part by Fonterra’s current Chief Technology Officer, Jeremy Hill.

Although unfortunate, it makes sense for Fonterra to have changed their stance on the A1 beta casein issue because much of their profit depends on selling milk that contains it. As we’ve seen many times, industry is often more concerned about profit than public health. Regardless of the ethics behind this, it’s up to you to make your own informed decisions based on the information available.

Due to some of the controversy surrounding the risks associated with A1 beta casein, the New Zealand Food Safety Authority (NZFSA) hired Professor Boyd Swinburn to conduct an analysis of the existing evidence.17 Unfortunately, Professor Swinburn was not previously involved with the A1 beta casein issue and was unaware of some of the research described earlier. Despite this, he still made it clear that the risks associated with A1 beta casein should be taken seriously and that further research should be done. He also stated that people may wish to avoid milk containing A1 beta casein as a precautionary measure. However, the NZFSA removed this section of the report without Swinburn’s knowledge and proceeded to issue a press release stating that there is no issue with A1 beta casein.18 Despite Swinburn’s disagreement with this statement, it was spread throughout the media and the concern of A1 beta casein was buried as an unimportant issue. The NZFSA has since published the lay summary that was originally removed from Swinburn’s report19, but this is after they already succeeded in dodging the A1 beta casein issue.

What You Can Do to Protect Yourself

There’s still a lot to learn about A1 beta casein and its association with illness and disease, but there’s certainly a lot of strong evidence indicating that it’s a problem. If you’re going to consume dairy, it may very well be in your best interest to choose dairy products that contain as little A1 beta casein as possible.

A1 beta casein is only produced by cattle belonging to the Bos taurus subspecies which predominately exist in the western hemisphere. The Guernsey breed tends to produce about 10% of their beta casein as A1, the Jersey breed tends to produce about 35%, and the Ayrshire, Holstein, and Freisian breeds tend to produce 50% or more. Goats don’t produce A1 beta casein which makes their milk and the dairy products derived from it an excellent alternative.

Even if produced from milk containing A1 beta casein, butter isn’t much of a concern because it contains very little protein. However, recent research has found that the simulated digestion of cheese, yogurt, and fermented milk can produce about the same amount of BCM7 as regular milk20 which makes them just as much of a concern.

Aside from avoiding A1 beta casein as much as possible, the most important thing you can do to protect yourself is to improve your digestive health by avoiding foods that promote intestinal inflammation. One of the easiest ways to do this is to base your diet mostly on natural whole foods. By improving your digestive health, your intestines will be better equipped to prevent BCM7 peptides and any other undesirable substances from being absorbed into your bloodstream where they can potentially provoke immune reactions and cause tissue damage.

As a preventative measure that doesn’t require much effort, some dairy farmers have been using selective breeding to ensure that none of their calves possess the gene required to produce A1 beta casein. Eventually, the herds belonging to these farmers will only consist of cattle that don’t produce A1 beta casein. As more consumers demand milk without A1 beta casein, dairy farmers will have more incentive to convert their herds.

For more information on the A1 beta casein issue and a thorough analysis of the research supporting and opposing it, I highly recommend reading Devil in the Milk by Keith Woodford.

[1. Hartwig A, Teschemacher H, Lehmann W, Gauly M, Erhardt G. "Influence of genetic polymorphism in bovine milk on the occurrence of bioactive peptides." Milk Protein Polymorphism. 1997. 459-460.]
[2. Sun Z, Cade JR. "A Peptide Found in Schizophrenia and Autism Causes Behavioral Changes in Rats." Autism. 1999. 3(1):85-89.]
[3. McLachlan. "β-casein A1, ischaemic heart disease mortality, and other illnesses." Medical Hypotheses. 2001. 56(2):262-272.]
[4. Laugesen M, Elliot R. "Ischaemic heart disease, Type 1 diabetes, and cow milk A1 β-casein." New Zealand Medical Journal. 2003. 116(1168).]
[5. Torreilles J, Guerin MC. "Casein-derived peptides promote peroxidase-dependent oxidation of human blood low-density lipoproteins." Comptes rendus des séances de la Société de biologie et de ses filiales. 1995. 189(5):933-942.]
[6. Tailford KA, Berry CL, Thomas AC, Campbell JH. "A casein variant in cow's milk is atherogenic." Atherosclerosis. 2003. 170(1):13-19.]
[7. Elliott RB, Harris DP, Hill JP, Bibby NJ, Wasmuth HE. "Type I (insulin-dependent) diabetes mellitus and cow milk: casein variant consumption." Diabetologia. 1999. 42(3):292-296.]
[8. Elliott RB, Wasmuth HE, Bibby NJ, Hill JP. "The role of beta-casein variants in the induction of insulin dependent diabetes in the non-obese diabetic mouse and humans." Milk Protein Polymorphism. 1997. 9702:445-453.]
[9. Beales PE, Elliott RB, Flohe S, Hill JP, Kolb H, Pozzilli P, Wang GS, Wasmuth H, Scott FW. "A multi-centre, blinded international trial of the effect of A1 and A2 β-casein variants on diabetes incidence in two rodent models of spontaneous Type I diabetes." Diabetologia. 2002. 45(9):1240-1246.]
[10. Padberg S, Schumm-Graeger PM, Petzoldt R, Becker F, Federlin K. "The significance of A1 and A2 antibodies against beta-casein in type-1 diabetes mellitus." Dtsch Med Wochenschr. 1999. 124(50):1518-1521.]
[11. Wikipedia. "Epidemiology of autism." cited 2010 February 3.]
[12. Panksepp J. "A neurochemical theory of autism." Trends in Neuroscience. 1979. 2:174-177.]
[13. Cade R, Privette M, Fregly M, Rowland N, Sun Z, Zele V, Wagemaker H, Edelstein C. "Autism and Schizophrenia:Intestinal Disorders." Nutritional Neuroscience. 2000. 3(1):57-72.]
[14. Sun Z, Cade JR, Fregly MJ, Privette RM. "ß-Casomorphin Induces Fos-Like Immunoreactivity in Discrete Brain Regions Relevant to Schizophrenia and Autism." Autism. 1999. 3(1):67-83.]
[15. Sun Z, Cade R. "Findings in normal rats following administration of gliadorphin-7 (GD-7)." Peptides. 2003. 24(2):321-323.]
[16. New Zealand Dairy Research Institute. "Milk containing beta-casein with proline at position 67 does not aggravate neurological disorders." 2001. International Patent Number WO 02/19832 A1.]
[17. New Zealand Food Safety Authority. "Beta casein A1 and A2 in milk and human health." 2004. cited 2010 February 3.]
[18. New Zealand Food Safety Authority. "A1/A2 milk review released." 2004. cited 2010 February 3.]
[19. New Zealand Food Safety Authority. "Beta casein A1 and A2 in milk and human health: Lay Summary." cited 2010 February 3.]
[20. De Noni I, Cattaneo S. "Occurrence of β-casomorphins 5 and 7 in commercial dairy products and in their digests following in vitro simulated gastro-intestinal digestion." Food Chemistry. 2010. 119(2):560-566.]

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