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Digesting dairy: What's the difference between A2 and ordinary milk?

a2 milk on display in stores
A2 milk is much more expensive than normal milk, despite production costs being the same.

ABC: Peter Barr

As lactose-free, soy and nut milks become more common household staples, there is another variety of milk that is becoming increasingly popular — A2 milk.

The milk is promoted and sold in supermarkets as an alternative for people who struggle to digest common varieties of cows' milk.

At $4.80 for two litres, consumers are paying more for A2 milk in the hope it won't upset their stomach — so what's the difference between A2 and other milk?

What exactly is A2 milk?

Over the past decade The a2 Milk Company, commonly known as a2, has become a major milk player in Australia with about 10 per cent of the market.

The New Zealand-based company owns the patent to the method for identifying the A2 milk cows, meaning it's the only brand that can sell milk with the A2 label.

A2 refers to the beta-casein proteins found in milk.

Depending on a cow's genetic make-up, it can produce either completely A1 beta-casein, a combination of both, or completely A2 beta-casein.

The two proteins alleles are almost identical but there are small variations and, while there is no strong scientific research, there is anecdotal evidence to suggest milk containing just the A2 protein is easier for some people to digest.

Natasha Murray is an accredited practising dietitian for Dietitians Association of Australia and said there was some — but not much — evidence showing the A2 protein was easier for people to digest.

"I've had a number of clients [with troubles digesting milk] say the A2 milk works better for them," she said.

How is it made?

Two cows stand in a paddock
A2 cows are exactly the same breed as other dairy cows, there is just a slight different in their genetic makeup.

ABC Rural: Tyne Logan

Unlike lactose-free milk alternatives, A2 milk production is exactly the same as normal milk production.

The difference comes in the breeding of the cows.

After testing cows to see if they produce A2 or A1 milk, farmers will work to breed out the A1 genetics from a cow.

Every cow must be tested before being approved to be used for A2 milk production.

Who should drink it?

Ms Murray said the people who would benefit from trialling the milk alternative were those who had digestion issues with dairy.

Facts: Milk allergies and intolerances

  • Approximately 1 in 50 infants have cow's milk protein allergies, but most grow out of it by the time they get to school
  • Up to 7.5 per cent of children have issues with cow's milk protein (either allergy or intolerance).
  • Lactose intolerance affects:
    7-20% of Caucasians
    65-75% of African Descent
    Over 90% in some Asian populations
    70% Australian Aboriginals.

A2 milk still contains lactose, so for some people who are lactose intolerant it will make no difference.

But Ms Murray said it could work.

"Some people may have reported having lactose intolerance but their symptoms are better with A2 milk, so it may be that their body is coping with just one issue rather than two issues at once."

Ms Murray said people who would most likely benefit from a2 milk, however, are those who are intolerant to the A1 protein.

She said if you had no issues digesting milk there was no point in buying a2 milk and if a person was allergic to cows milk protein this would not work.

There have been some suggestions that the A1 protein has negative impacts on health, such as inflammation of the gut, but these have only been trialled on animals which Ms Murray said was difficult to translate to human examples.

Why is it more expensive?

In shops, a2 milk retails at approximately 50 per cent above the value of other common non-a2 milk products, despite production costs being almost identical to ordinary milk production.

According to a spokesperson for The A2 Milk Company this is because the company pays suppliers a premium price for the milk.

It can take a farmer more than five years of constant testing to breed a herd that has 100 per cent A2 genetics.

Farmers also have to spend more time testing the genetics of the each cow when they're purchased or born.