What’s the Deal with A2 Milk?

Adventures with industry-funded studies

Image courtesy of The a2 Milk Company Limited

There’s a lot of division in this country, but one thing I think we can all agree upon is that there are too many milks now. You’ve got your soy milk, nut milks, hemp milk, oat milk, goat milk, and the very unfortunately named pea milk. Even in the cow category, it’s not just conventional and organic anymore. There’s grass-fed and there’s lactose-free.

Then, a few years ago, something called A2 milk burst onto the scene. Now it’s finding its way into yogurt, ice cream, infant formula, even fancy baby food pouches. And you know that once something is in fancy baby food, it’s a bona fide wellness trend.  

But, as with so many wellness trends, all the A2 hype may be just that: hype, much of it fueled by the very people making money off the latest arrival in the dairy aisle… 

So what is A2 milk, and why should I care? 

The protein in cow’s milk is divided between two types: whey and casein. A portion of the casein is beta-casein, the two most common variants of which are called A1 and A2. They differ from each other by a single amino acid. That tiny distinction leads them to be digested differently. When broken down, A1 beta-casein releases a compound called — stay with me — bioactive opioid peptide β-casomorphin 7, or BCM-7. Some say that BCM-7 increases digestive upset, as well as the risk for cardiovascular diseases, type I diabetes, even autism and schizophrenia. 

A2 milk, sometimes written as A2/A2 milk, is cow’s milk that doesn’t contain A1 beta-casein.

How do you even get cow’s milk without A1 beta-casein?

Certain breeds of cow naturally produce little or no A1 beta-casein; others, like America’s favorite dairy cow, the Holstein Friesian, tend to produce milk that contains both A2 and A1 proteins. It’s thought that all cows produced milk without A1 beta-casein until a genetic mutation snuck into European dairy herds a few thousand years ago.  

A simple genetic test allows dairy farmers to identify which cows will produce A2-only milk, and create herds of those cows. For reference, the milk of most other mammals (including humans) does not contain A1 proteins.  

Okay, so why do we think that A1 beta-casein is so bad?

In the early 1990s, scientists in New Zealand began studying the overlap between places with higher incidences of chronic diseases like heart disease and type 1 diabetes, and dairy cows that produced milk with higher levels of A1 beta-casein. It looked like there could be a connection. 

Naturally, this hypothesis generated a lot of media attention – we’re all suckers for a new dietary villain! In 2000, one of those Kiwi researchers teamed up with one of New Zealand’s richest men to seize the commercial opportunity. They formed the A2 Corporation (now called The a2 Milk Company). Initially, the company sold farmers the genetic test kit to determine whether a cow would produce milk with or without A1 proteins. Later, it moved into marketing A2 milk, first in New Zealand and then internationally. 

Over the years, A2 milk has become increasingly popular across Australia, New Zealand, the U.S., and China (it flopped in the UK). If you’ve come across A2 milk in the grocery store, it’s probably a2 Milk Company’s products you’ve seen. Today the New Zealand company is still the global leader in A2 milk distribution, and its products retail for about twice the price of conventional milk.

Are the concerns about A1 beta-casein legit? 

The short answer is: mostly, no.  

That original A1 hypothesis was based on observational studies looking at correlations between A1 beta-casein intake and how common diseases like type 1 diabetes and coronary heart disease were in various countries. These types of studies are problematic for a whole bunch of reasons, and when it comes to nutrition research, they are known to be unreliable. 

The animal studies that followed did show some evidence that A1 beta-casein could have negative health effects – on rabbits and mice, at least – although some of those have been discredited as flawed by other researchers. There have been only a handful of human studies of this issue to date, and those have failed to show a compelling link between A1 beta-casein and negative health impacts. 

In 2009, the European Food Safety Administration did a full review of the literature and found no conclusive evidence of a link between A1 beta-casein and chronic diseases. Another 2020 literature review arrived at the same conclusion. 

The only area where the research has shown a consistent benefit to A2 milk: digestive intolerance. For people who report symptoms of discomfort after consuming milk, studies have shown that these are sometimes improved by drinking A2 milk. 

But – BUT! – the five human studies I came across suggesting that A2 milk was easier to digest were all funded by the a2 Milk Company. While this doesn’t necessarily mean the conclusions are incorrect, it makes it very hard to have confidence in the findings.

So, should I buy A2 milk?

If you’re having digestive issues after drinking milk — and lactose-free milk doesn’t fix the problem — there’s a chance that it’s because you’re intolerant to A1 beta-casein, not lactose. It could be worth trying A2 milk. You could, of course, also stick to plant-based milks. But, if you prefer cow’s milk, A2 milk is an option. 

If you’re able to drink cow’s milk with no issues, there’s no clear reason to pay more for A2 milk. 

If hearing all the things that might possibly maybe be bad about A1 beta-casein freaks you out (Inflammation! Oxidative stress! Coronary heart disease!), and you’d rather buy A2 milk as a better-safe-than-sorry thing, there’s really no downside — apart from the price. 

For those of you willing to pay up for A2: we recommend going the extra mile to buy a product that’s also organic and grass-fed, like the ones sold by Alexandre Family Farm. a2 Milk Company’s products are not organic, but the brand did recently release a grass-fed line, sold primarily at Whole Foods. If you’re going the fancy milk route, it makes sense to choose one held to higher farming standards.