Milk is a good source of nutrients and protein, but some people just can't stomach it.
New research from Liggins Institute at Auckland University shows A2 milk could be a solution.
"A2 protein is digested easier," says Professor David Cameron-Smith.
"We've got lots of evidence of the way in which it's digested, this is the first human evidence to show there really is a difference."
An estimated 20 to 30 percent of Kiwis are lactose intolerant. Worldwide, that number is as high as 70 percent, researchers say.
In a small trial, a group of 30 women who had trouble digesting milk were given lactose-free milk as well as A2 milk and conventional milk.
"We found a strikingly different pattern of digestive symptoms in people we identified as lactose intolerant after drinking A2 milk compared to conventional milk," study lead Dr Amber Milan told Newshub.
"A2 milk was at least as effective as lactose-free milk at preventing or easing some of the symptoms of lactose intolerance, including nausea, stomach pain and bloating, but didn't reduce levels of flatulence and gastric reflux."
"There is some evidence that the symptoms of lactose intolerance may be influenced by the proteins in milk," says AgResearch scientist Matthew Barnett.
One theory is that A1 protein type causes inflammation in the small intestine, which exacerbates lactose intolerance symptoms.
Conventional milk contains both the A1 and A2 types of protein. It's thought that originally all cows produced only the A2 protein type, and the A1 mutation appeared 5000-10,000 years ago. But some dairy cows naturally produce only the A2 type.
A2 milk is harder to get hold of and more expensive to process; one 2L bottle purchased by Newshub cost $7.29.
But scientists at the Liggins Institute hope it could be another option for people who have avoided lactose, and another opportunity for the New Zealand dairy industry.
Though Fonterra says it's too early to draw any firm conclusions and further trials are needed.
The study was funded through the New Zealand Government High-Value Nutrition National Science Challenge, with co-funding from The A2 Milk Company Limited. The findings are being presented today at the Food and Nutrition Conference and Expo in Chicago.