There's another boost to producers of A2 milk, from a study carried out by Auckland University.

The research compared how people with a dairy intolerance coped with A2 milk, with conventional milk products.

The study found a big difference in the effects of A2 milk compared with conventional milk, among people diagnosed as lactose intolerant.

Professor David Cameron-Smith said it suggests people diagnosed as lactose intolerant can handle the A2 protein much better.

"What we think is happening is that when people consume A2 protein they're able to digest it, it doesn't result in the same level of potential inflammation that you find in people that have intestinal problems to milk."

Cameron-Smith said it's good news for people who'd otherwise have to avoid drinking milk.

"For women who are lactose intolerant consuming normal milk leads to pain and anguish and gastro-intestinal problems, whereas if they consumed A2 milk they had very few symptoms."