Milking the health advantages of A2

By SIMON COLLINS

A 9-year-old Australian girl has found a completely unexpected benefit from a natural human experiment with "A2 milk".

A2 Corporation, the Auckland-based company that has launched a genetic variety of cow's milk called A2 in northern New South Wales, has concentrated its publicity on evidence that A2 milk may reduce Type 1 diabetes and heart disease.

But its long-awaited commercial launch brought a surprise email last week from the mother of a girl in Byron Bay with a problem the company has never made any claims about: a simple milk allergy.

"My daughter is 9 years old and can only have milk in very small quantities. It makes her sick," the mother said. "I purchased your milk and after a full glass she hadn't reacted. She subsequently drank one litre of milk over three hours and was not sick."

A2 Corporation chief executive Dr Corrie McLachlan says he has received "two or three other" letters or emails from mothers of children with similar milk allergies. For the moment, he refuses to give any more details.

"We are collating responses similar to the one I read to you. Our communications consultants wish to sit on the information."

So far New Zealand's dairy giant, Fonterra, is unmoved. On March 28 it said there was "no valid scientific evidence currently available to Fonterra, published or otherwise, that milk with the A1 beta-casein causes the negative health effects claimed by A2 Corporation".

Despite researching the issue itself since the early 1990s, Fonterra refuses to produce A2 milk. Research and development director Dr Chris Mallett says it could market it only by claiming health benefits which have not been proven.

A2 Corporation plans to let consumers decide for themselves by launching A2 milk on the New Zealand market this month - at least in Christchurch, and possibly also in the North Island.

What is A2 milk?

Disregarding water, the solid content of milk is broadly one-third fatty hydrocarbons (molecules of hydrogen and carbon atoms), one-third starchy carbohydrates (carbon, hydrogen and oxygen) and a quarter proteins (carbon, hydrogen, oxygen plus nitrogen and often sulphur), plus a small amount of ash.

Proteins are the main ingredients in our muscles, bones, skin and hair. They are made out of about 20 repeating smaller units called amino acids, linked up in numerous combinations by peptide bonds.

The main protein in milk is called casein, and comes in varieties called alpha, beta and kappa, each with a slightly different order of amino acids.

Beta-caseins in turn come in two main variants, called A1 and A2. The order of amino acids in A1 and A2 beta-caseins is identical except at the 67th position in the chain, where the A1 protein has a particular amino acid which causes the chain to break at that point when the body digests food, releasing a smaller "peptide" called beta casomorphin-7 (BCM-7) into the body.

The A2 protein has a different amino acid in position 67, which prevents the protein breaking up.

Between 30 and 40 per cent of New Zealand cows have only A2 beta-caseins, producing "A2 milk". The rest of our cows have either pure A1 or a mixture of A1 and A2.

What does A2 Corporation claim? A2 Corporation was formed in 2000 by chemical engineer McLachlan and Dunedin entrepreneur Howard Paterson, and launched A2 milk in northern New South Wales on March 10.

The company claims:

pf* Type 1 diabetes, which usually starts in childhood and requires frequent insulin injections, is most common in countries that drink the most A1 milk. This link is borne out by an Auckland study by Dr Bob Elliott where mice fed A1 milk developed more diabetes than those fed A2 milk.

pf* Deaths from coronary heart disease are also highest in countries drinking the most A1 milk. This link is borne out by a new study by Brisbane's Dr Julie Campbell, who found that rabbits fed A1 milk suffered damaged veins but those fed A2 milk did not.

pf* Deaths from mental disorders such as autism and schizophrenia are also highest in countries drinking the most A1 milk. This link is borne out by US studies finding BCM-7 and similar peptides in the urine of autistic children but not in normal children.

How does Fonterra respond to that?

Mallett says none of the correlations between various diseases and A1 milk prove anything other than a starting point for research.

"There is a correlation between wearing a skirt and breast cancer," he says.

"That does not mean there's a causal connection. It just so happens that women get breast cancer and women wear skirts."

Fonterra's predecessor, the Dairy Board, funded a major test of the diabetes link using mice in Auckland and London and rats in Ottawa. In each case, the animals were fed two different base diets, each with A1 and A2 milk variations, making a total of six experiments.

In one of the two Ottawa experiments, the rats fed A1 milk developed more diabetes than those on A2 milk. But in the other Ottawa case and in both London cases, A1 or A2 milk made no difference. In Auckland, the mice died because of a technical mistake.

The Ottawa scientist who wrote up the results, Dr Fraser Scott, concluded that if A1 milk did help cause diabetes, it was only in combination with other things in the diet.

Fonterra also tested the link between milk protein consumption and deaths from heart disease. It found that a strong correlation that existed in the 1970s had disappeared by the 1990s, suggesting other causes of heart disease were more important.

What is the evidence for diabetes?

The Scott study shows that even if A1 milk is one of the factors making you more likely to get Type 1 diabetes, it is only one factor among several.

The dominant factor is genetic.

Elliott, who has spent his life looking for a cure for diabetes, says only 0.5 per cent of children have antibodies in their blood showing that they are genetically prone to Type 1 diabetes, and, of those, only some develop the disease.

But 15 years ago Elliott noticed that Type 1 diabetes was much more common among Samoan children in New Zealand than those who stayed in Samoa, despite the same genetic background. He suspected this might be because children drank more milk in New Zealand.

His latest statistical study, published in the NZ Medical Journal in January with former Health Department public health specialist Dr Murray Laugesen, tested links between childhood Type 1 diabetes rates and supplies of 175 foods in 18 countries. The strongest correlation was with A1 milk.

However, it also noted that consumption of A1 milk per person actually declined by 0.6 per cent a year in those countries from 1960 to 1996, while Type 1 diabetes rates rose by 3 per cent a year.

Elliott explains that his figures of total food supplies in each country did not necessarily match trends in actual food consumption by children. Children might be consuming more milk, in yoghurt for example, even while total milk supply declined.

But in that case, any correlation between total food supplies and childhood diabetes would be meaningless. Clearly, further animal trials and then human trials would be needed to prove a link.

In the meantime, Auckland University diabetes expert Dr Garth Cooper says: "I have not seen anything about Type 1 diabetes that would convince me that I would recommend to a patient that they should be cautious [about A1 milk]."

What is the evidence for heart disease?

Even though he is unconvinced on the diabetes link, Cooper believes Campbell's A2 Corporation-funded rabbit study in Brisbane established "a case to answer" for a link between A1 milk and heart disease.

Campbell, director of Queensland University's Vascular Biology Centre, took 10 groups of rabbits and fed them A1 or A2 milk or whey as a control group, with or without adding cholesterol to their diet, and with or without damaging the walls of the rabbits' blood vessels by inserting a tiny balloon on the end of a catheter.

The injuries simulated the aged blood vessels of human adults, while the uninjured rabbits simulated human children.

The results showed that rabbits fed A1 milk developed much higher cholesterol levels than those fed A2 or whey.

In addition, the uninjured ("juvenile") rabbits fed A1 milk developed bad fatty streaks in their arteries. But A1 milk made no significant difference to fatty lesions in the injured ("adult") rabbits.

"If this rabbit model is translated to humans - and I'm not necessarily saying that it can be - then what it might mean is that the type of milk that you drink in childhood might impact on whether or not you develop more or fewer of those juvenile fatty streaks that have the potential to go on to form adult lesions," Campbell told the Herald. "That means it may be important for children of families with a predisposition to cardiovascular disease to drink A2 milk."

Her findings support the statistical evidence, also reported in January by Elliott and Laugesen, that the link between deaths from heart disease and A1 milk supply across 18 countries was stronger than correlations with any other kind of food.

However, another A2 Corporation-funded study, using mice and led by Dr Greg Dusting at Melbourne University's Howard Florey Institute, has found the opposite.

Using a breed of mice that had been genetically engineered to be susceptible to heart disease, Dusting fed one group a diet containing A1 milk and another group A2. The A2 group developed slightly more lesions in their arteries than the A1 group.

"That was completely the opposite of what we expected," he told an Australian Four Corners documentary last week.

A2 Corporation scientist Andrew Clarke said Dusting's results were incomplete because he did not include control groups of mice not susceptible to heart disease.

Campbell also dismisses Dusting's mice experiments compared with her rabbits.

"Rabbits, while they are vegetarian and don't normally drink milk, carry their cholesterol in a very similar way to the way humans do. Rats and mice carry their cholesterol completely differently."

However, even Campbell agrees that her results are only an initial experiment. She is not prepared to recommend that people should drink A2 milk.

"It's too soon to make definitive conclusions that have a health message," she said.

"We need another five years of study before we would be prepared to go and make blanket statements."

4corners (then search for "white mischief")