A1 & A2 MILK
- MILK PROTEINS AND HUMAN HEALTH: A1/A2 MILK HYPOTHESIS.
Milk from dairy cows has been regarded as nature’s perfect food, providing an important source of nutrients including high quality proteins, carbohydrates and selected micronutrients. More than 95% of the cow milk proteins are constituted by caseins and whey proteins. Among the caseins, beta casein is the second most abundant protein and has excellent nutritional balance of amino acids. Different mutations in bovine beta casein gene have led to 12 genetic variants and out of these A1 and A2 are the most common. The A1 and A2 variants of beta casein differ at amino acid position 67 with histidine (CAT) in A1 and proline (CCT) in A2 milk as a result of single nucleotide difference. This polymorphism leads to a key conformational change in the secondary structure of expressed β-casein protein. Gastrointestinal proteolytic digestion of A1 variant of β-casein (raw/processed milk) leads to generation of bioactive peptide, beta casomorphin 7 (BCM7). Infants may absorb BCM-7 due to an immature gastrointestinal tract whereas adults gather the biological activity locally on the intestinal brush boarder. In hydrolysed milk with variant A1 of beta-casein, BCM-7 level is 4-fold higher than in A2 milk. Initial studies on indigenous cow (Zebu type), buffalo and exotic cows (taurine type) have revealed that A1 allele is more frequent in exotic cattle while Indian native dairy cow and buffalo have only A2 allele, and hence are a source for safe milk.
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.
This review outlines a hypothesis that A1 one of the common variants of beta-casein, a major protein in cows milk could facilitate the immunological processes that lead to type I diabetes (DM-I). It was subsequently suggested that A1 beta-casein may also be a risk factor for coronary heart disease (CHD), based on between-country correlations of CHD mortality with estimated national consumption of A1 beta-casein in a selected number of developed countries. A company, A2 Corporation was set up in New Zealand in the late 1990s to test cows and market milk in several countries with only the A2 variant of beta-casein, which appeared not to have the disadvantages of A1 beta-casein. The A1/A2 milk hypothesis was ingenious. If the scientific evidence had worked out it would have required huge adjustments in the world’s dairy industries.
- DEVIL IN THE MILK :
“We’ve got a huge amount of observational evidence that a lot of people can digest the A2 but not the A1,” says Keith Woodford, a professor of farm management and agribusiness at New Zealand’s Lincoln University who wrote the 2007 book Devil in the Milk: Illness, Health, and the Politics of A1 and A2 Milk. “More than 100 studies suggest links between the A1 protein and a whole range of health conditions”—everything from heart disease to diabetes to autism, Woodford says, though the evidence is far from conclusive.
The A1 milk hypothesis was devised in 1993 by Bob Elliott, a professor of child health research at the University of Auckland. Elliott believed that consumption of A1 milk could account for the unusually high incidence of type-1 diabetes among Samoan children growing up in New Zealand. He and a colleague, Corran McLachlan, later compared the per capita consumption of A1 milk to the prevalence of diabetes and heart disease in 20 countries and came up with strong correlations. Critics argued that the relationships could be explained away by other factors, such as diet, lifestyle, and latitude-dependent exposure to vitamin D in sunlight—and in any case started to fall apart when more countries were included.
- 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.
- WHAT DOES THIS HAVE TO DO WITH FOOD SAFETY…?
Some people who have turned to raw milk (milk that hasn’t been pasteurized to kill harmful germs) have said they made that choice because drinking pasteurized milk upsets their digestive system. The company believes that its a2 Milk, which is pasteurized, will offer those people an option — one that bypasses the risk of becoming ill with a foodborne illnesses such as E. coli, Campylobacter, Salmonella, and Listeria, pathogens which can contaminate raw milk. Statistics from the U.S. Centers for Disease Control and Prevention (CDC) reveal that from 1998 through 2011, 148 outbreaks due to consumption of raw milk or raw milk products were reported to the agency. These resulted in 2,384 illnesses, 284 hospitalizations, and 2 deaths. The bacteria in raw milk can be especially dangerous to people with weakened immune systems, older adults, pregnant women, and children. A CDC analysis also found that foodborne illness from raw milk especially affected children and teenagers.
- THE NUTS AND BOLTS:
The company’s a2 Milk (whole milk, 2 percent milk, 1 percent milk, and fat-free milk) will be sold in half-gallon containers for $4 to $4.50 Nathan said the company has perfected a patented testing process for A2, and that farmers would need to get permission to market and sell a2 Milk.
According to the company’s website, testing is done by using a simple and non-invasive DNA test that analyzes a strand of hair from the tail of each dairy cow. The A2-certified cows are then segregated and milked separately to produce a2 Milk. For consumers in other states who want to get a higher-than-average A2 content in the milk they buy, the best route is to get it from a dairy whose cows are A2-dominant breeds such as Jersey, Guernsey, Normande, and Brown Swiss.
- A1 & A2 GENETICS:
At this time, there are plenty of A2/A2 sires available especially in full-sized breeds; therefore, we see no reason not to breed only A2. If you breed an A1/A1 dam to an A2/A2 sire, you will throw an A1/A2 as they get one from each side. If you breed an A1/A2 dam to an A2/A2 sire, you have a 50% chance of throwing A2/A2. What can you do? You can ask your source for local milk if they are breeding for A2/A2 milk. If they do not understand it, you can refer them to me or this article. Real Milk.com is one resource to find a local herd share program. Your local farmers market or CSA, which can be found at Local Harvest org would be another. Please do not contact them to ask if you can buy milk unless it is legal in your state. You can sometimes find farms that let you buy a share of the herd and pay the farmer to care for your cow. In exchange, you get to enjoy all the benefits of co-owning a cow such as milk (obviously) and manure for your garden. You could also consider purchasing your own milk goat (they do not carry the A1 gene), buy a cow with A2 genetics, or buy a cow with the plan to breed A2 genetics and select future heifers.