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What is A2 milk? Everything you need to know

Just one protein differentiates A2 milk from "conventional" dairy milk.

For those who have trouble digesting milk, an alternative option could make it easier on their stomachs.

A2 milk has been on the market for over two decades, but the distribution was limited. Now, fifth-generation farmers Blake and Stephanie Alexandre will be selling their farm's brand of A2 milk in Whole Foods, making them the first organic farm in the U.S. to sell it.

What is A2 milk?

The difference between A2 milk and A1 milk is just one protein. According to licensed nutritionist Monica Reinagel, the primary protein in cow's milk is known as beta casein, which can be present in one of two forms. Those forms are known as the A1 form and A2 form, and most cows produce both, so most milk in stores has both A1 and A2 proteins.

"If you're just grabbing milk off the shelf then most likely that milk is going to contain both the A1 form and the A2 form of beta-casein," said Reinagel. Beyond that change in the protein, Reinagel said A2 milk is "nutritionally identical" to regular milk.

Blake Alexandre said it took about 13 years to develop a herd of all A2 cows.

"You would not be able to taste a difference or see a difference, unless you put it under a microscope," Reinagel said.

Reinagel explained that it seems that the A2 protein was more common "before dairy cattle were domesticated," and as they began to be domesticated, a "random, natural genetic mutation happened" that led to some cows starting to produce the A1 form of milk. That genetic mutation became predominant, especially in North America.

"Most of the dairy cattle here in the United States produce milk that contains both A1 and A2 types of that beta casein protein," said Reinagel. "There are still cattle in Asia and elsewhere in the world that produce more (of) the A2 kind, and now we're starting to select and breed for that characteristic in cows so we can produce milk that contains only the A2 variation."

How do farms produce A2 milk?

Since only some cows can produce A2 milk, farms have to specifically seek out cows that produce that type of milk. The Alexandres said that it took about 13 years to develop a herd that only produced A2 milk.

"It wasn't quite that bad," said Blake Alexandre. When they tested the cows in the herd, they found that about 35% of the population was already producing A2 milk, so it was "just a matter of identifying and segregating cows" and "only bringing in new genetics that are A2/A2."

But how does the American dairy industry feel about A2 milk? Pretty open to it, it seems — if it ultimately means more real-dairy consumers. Paul Ziemnisky, Executive Vice President, Global Innovation Partnerships at Dairy Management Inc., told TODAY in an emailed statement, "We are focused on bringing value-added innovation and growth to the fluid milk category … Newer offerings within fluid milk, like fairlife and A2, are just a few examples of the innovation helping to ignite the category … and ultimately give consumers even more reasons to choose real dairy."

Who can benefit from drinking A2 milk?

Reinagel said that people who have difficulty digesting milk may have less trouble when drinking A2 milk, but beyond that, there's "no other known benefits to drinking milk that only contains the A2 protein."

"If you don't have any trouble drinking milk, there would not really be any reason for you to pay extra for the A2 milk, because there's no other known benefit to that, and there's no known risks to drinking A1 milk," she said.

However, if you're among the 25% of the Western population that has "some sort of digestive distress" when drinking cow's milk, A2 milk could help.

"Some people have difficulty digesting milk … maybe some bloating or gas or something like that, and this is thought to be due to an inability to process lactose in the milk," Reinagel explained. "There are some studies showing that for people that have this lactose intolerance, drinking milk that only contains that A2 form of the protein can reduce some of those symptoms, which is odd, because A2 milk contains the same amount of lactose as regular milk.'

Recent small studies appeared to show that the A2 milk led to less distress: A 2020 study involving 40 women showed that lactose intolerant women drinking conventional milk experienced "prolonged digestive discomfort," while "A2 milk reduced some symptoms" including nausea and fecal urgency. Another 2020 study of 33 people "demonstrated that (A2 milk) causes fewer symptoms of lactose intolerance" than conventional milk.

A 2019 study of 75 Chinese preschoolers compared the effects of 5 days of conventional milk consumption against that of A2 milk. The study showed that the children who consumed just A2 milk had "significantly less severe gastrointestinal symptoms," and "no severe adverse events related to consumption of either milk product."

How do I know if A2 milk is right for me?

Since there are no known risks to drinking A2 milk, Reinagel said that anyone who experiences digestive distress when drinking milk could try A2 milk or other options like lactose-free milk or a lactose supplement.

"They've done studies both on people that are known to be lactose intolerant and also people who just sort of suspect that they may have some trouble because they've experienced these symptoms," Reinagel explained. "And in both of those groups, some people reported fewer symptoms when they drink the A2 milk."

"I think there's more to understand about why it might have this effect," she continued. "But in the meantime, I think this is one of those things that individuals are going to need to try for themselves to see whether it does or doesn't make a difference for them."

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Gadi Schwartz and Sammi Davis contributed.