What Is a2 Milk—and Should You Be Drinking It?

Photo: a2 Milk

Drinking cow's milk is always a hotly contested nutritional debate—should you drink skim or whole? Or should you not drink it at all and switch to non-dairy milk?

Regardless of the milk team you bat for, it's no surprise that cow's milk and dairy, in general, can cause stomach problems for some people who have trouble digesting it, which is partly why many are switching over to plant-based alternatives. (FYI, if you still don't know whether you have a dairy allergy or just an intolerance, here's the difference.)

But a2 Milk, which was designed to solve that problem, falls into a weird in-between category. The milk option is marketed as "100 percent real milk that's easier on digestion", and it's gaining a ton of popularity. The company has made deals with Kroger, Walmart, and Costco in the United States, according to Forbes—and it's now available in over 12,000 U.S. stores since it debuted here in 2015. (You can use their a2 Milk finder here.)

Here, we break down what a2 Milk really is—and whether or not you should make the switch.

What Is a2 Milk?

First, the basics. Cow's milk is made up of two milk proteins—whey and casein. There are 12 different types of casein proteins, and the most common are called A1 and A2.

"A1 and A2 are the beta-casein proteins naturally found in milk," says Vandana Sheth, a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. "Normal cow's milk contains a combination of both A1 and A2. Although the difference between A1 and A2 is small, the difference plays a key role in how the protein is digested," says Sheth.

That's because when A1 protein is broken down, it creates a protein fragment called beta-casomorphin-7 (BCM-7), which is believed to cause dairy's digestive discomfort. When A2 Milk is broken down, there is no BCM-7 created.

Translation: a2 Milk tastes the same as the regular old milk you grew up drinking, but contains only the A2 protein, which may minimize stomach discomfort in some people, Sheth explains. And this is the biggest argument a2 Milk has going for it.

A 2017 study published in Nutrition Journal found that among participants who identified as lactose intolerant, milk containing only A2 beta-casein protein produced fewer gastrointestinal symptoms (like bloating, gas and abdominal pain) compared to regular milk, supporting the idea that it may be easier to digest than normal milk.

Where Did a2 Milk Start?

Although you may have only seen commercials for the stuff recently, a2 Milk has been on the market in Australia for years.

According to Quartz, it all began in the 1990s, when New Zealand–based scientist and entrepreneur Corran McLachlan discovered the A1 and A2 proteins in cow's milk. He found that many people who experience symptoms from drinking milk just have trouble digesting the A1 protein. He created a2 so that milk lovers wouldn't be forced to make any compromises on taste or nutrition that may come with switching to a plant-based or lactose-free option.

Is a2 Milk Lactose-Free?

One big point to clarify: a2 Milk contains the same amount of lactose as ordinary cow's milk. So while a2 Milk may help people with dairy sensitivity or milk protein intolerance, it's not for those who are specifically lactose intolerant.

FYI, lactose intolerance is difficulty digesting lactose, the natural sugar found in milk, due to a lack of the enzyme lactase, which is needed to digest lactose. The digestive disorder is genetic and affects 30 to 50 million Americans. It also occurs more in people of African, Asian, and Hispanic ancestry, according to the Mayo Clinic.

Although a2 milk has been shown to be helpful to those with lactose intolerance, because of the limited amount of research that has been done, it's not enough to back up a2 Milk as a verified drink for those with lactose intolerance. So if you have a cow's milk or lactose allergy or are lactose intolerant, you should stay away.

Should You Try a2 Milk?

Bottom line: There's really nothing to lose. "A2 milk is (still) cow's milk and provides all the same nutrition profile and benefits as normal cow's milk, with easier digestion for some people who may have a harder time digesting normal milk," says Sheth. (FYI, here's a handy chart to help you choose from 13 different types of milk.)

Oh and ICYMI, cow's milk offers tons of nutritional benefits that many milk alternatives don't. So if you're only drinking oat or almond milk to avoid stomach discomfort (and aren't truly lactose intolerant), you may want to switch back to good ol' cow's milk for the calcium, vitamin D, phosphorous, potassium, and protein it offers.