People in the UK could soon get the chance to buy a type of milk which, it is claimed, could be safer for the heart than ordinary milk.
A1 milk is less healthy, claim some scientists
Most of the milk sold in the UK contains particular proteins - called "A1" - which some researchers have claimed could increase the risk of heart disease.
Although this link has not been scientifically proven, producers in the UK are preparing to offer an alternative - a milk which does not contain the A1 proteins.
This "A2" milk would be marketed at approximately five pence a pint more than standard milk.
It comes from herds which naturally produce milk with much lower levels of the A1 proteins.
Many farmers in Australia and New Zealand have A2 herds, and the milk is popular among consumers there.
In the UK, only a few herds in the Channel Island of Guernsey are A2 producers.
Companies planning to market A2 milk say that it is hard to satisfy demand.
Farmer Rod Kent from Berkshire plans to own the first A2 herd in the country.
His cows are being tested to make sure they are all A2 producers.
He told the BBC: "All milk is good for you, but if this is good for some particular small segment of the population let them have the choice."
However, Professor Jeremy Pearson, from the British Heart Foundation, said that the advantage, if any, would probably only be slight.
He said: "I think there would be far more effect on the incidence of heart disease from switching from full fat to semi skimmed rather than switching from A1 to A2.
"The research done so far is preliminary - it might have an effect on heart disease but we are a long way from saying the effect on human disease."
Some scientists theorise that A1 may be a factor in the high rates of cardiovascular disease in some parts of the UK.
Dr Corrie McLachlan, who runs a company which is marketing A2 milk, claims that, for example, people in Northern Ireland - which has high rates - drink far more A1 milk than many other parts of the UK.
However, spokesmen for the Dairy Council, and other scientists, insist that no proof of this link has been forthcoming.
There have also been claims that the A2 milk could be beneficial to autistic children, but again, proof is so far lacking.
However, Brenda O'Reilly from the charity "Autism Unravelled", said: "I think it's very important to do scientific research to show A2 would be a good alternative, and important to children because they love milk and it would be so nice to offer an alternative."