What Is A2 Milk and Is It Really Healthier?

In the latest episode of Gastropod, co-hosts Cynthia Graber and Nicola Twilley answer a few of the great questions they’ve received from listeners over the years, including the mystery behind A2 milk. The two other questions answered in the episode: Are hush puppies racist? And why do so many weddings need a fancy cake?

You might have noticed that, alongside fat-free, 2%, and whole milk, the dairy aisle of your grocery store has begun to stock cartons of milk with an odd name: A2 Milk. The label and advertising claim that A2 milk is easier for dairy intolerant folks to digest. But is A2 milk the relief that those who can’t consume dairy without discomfort have been waiting for — and, for that matter, should we all be drinking it?

What is A2 milk?

To find out, Gastropod called up Dennis Savaiano, a researcher at Purdue University who has been studying milk intolerance since the 1980s. Turns out that milk is made up of a number of different components: one of those is lactose, the primary sugar in milk, and another is casein, the primary protein in milk. There are different types of casein, but the main one found in cow milk is called beta casein. Then—because biology is complicated—there are different types of beta casein, which vary by one or two amino acids (the building blocks of proteins), and the main flavors of beta casein are called A1 and A2. So, basically, A2 is a particular variation of the protein in milk.

To make things yet more confusing, A2 milk is older than A1 milk. Dennis told us that up until somewhere between 5,000 to 10,000 years ago, all cows’ milk contained the A2 variety of beta casein. Then, at some point, a normal and harmless random genetic mutation occurred that led some cows to produce milk with one different amino acid in the protein—milk that we now know as A1. Today, many traditional breeds of cattle, including those found in Africa and Asia, produce A2 milk; other heritage breeds such as Jersey and Brown Swiss produce a mix of A1 and A2 milk (usually majority A2); and the classic cows of Western industrial dairy production, the Holstein and the Friesian, produce majority A1 milk.

If the cows don’t care, why should we?

In the 1990s, some researchers in New Zealand claimed that drinking A1 milk was leading to higher levels of diabetes in children. If that’s not enough, they also suggested that A1 might be contributing to heart disease, and perhaps even to rising levels of schizophrenia and autism. They blamed this on the fact that A1 milk seems to cause inflammation in the digestive system. They suspected that this is because, thanks to that single amino acid difference, when the protein in A1 milk breaks down in the digestive tract, it produces a substance that’s similar to morphine and latches onto morphine receptors in the gut. (No, it doesn’t make you high, because morphine needs to reach your central nervous system, particularly the brain, to do so. Morphine receptors in the gut seem to be involved in how quickly things move through the digestive tract.)

In any case, the researchers partnered with entrepreneurs to sell A2 milk, and its popularity spread. They also funded a number of studies that seemed to suggest that A2 milk was more easily digested than A1 milk, that it could provide relief for those who suffer after consuming dairy—that maybe people who believe they can’t tolerate lactose actually can’t tolerate the A1 form of casein.

So is the A2 milk hype real?

Over the past decades, scientists have studied the issue and have not been able to find good evidence for the most serious of the health claims, such as the link between A1 milk and childhood diabetes, schizophrenia, and autism.

Dennis Savaiano told us he was skeptical of the digestive claims as well, until just a few years ago. That’s when the A2 company reached out to him to ask if he would conduct a study on whether people who are dairy intolerant might be able to more comfortably consume the A2 variety. “I said, great, it’s not going to work,” Savaiano told Gastropod. “I’ll take your money. I’ll do the study. It’s not going to work. I’m going to show it doesn’t work.”

He’s not the only one who took this challenge on: Gastropod’s own intrepid reporter, Cynthia Graber, who regularly feels pain and nausea after consuming dairy, decided to test this for herself. What did they discover? You’ll have to listen to Gastropod to find out!