Your Dairy ‘Allergy’ Isn’t Real—’The Art of Being Well’ Explains the Genetic Mutation That’s Been Ruining Your Gut

Bloated after a latte but somehow fine with cheese? Welcome to the dairy confusion club. On The Art of Being Well, host Dr. Will Cole sits with Jeff Mroz—former NFL player on a mission to fix milk’s reputation—to unpack why so many of us blame lactose when the real trigger may be a protein hiding in your daily pour.

“The 70 percent of the world’s population that are told they’re lactose intolerant might not actually be lactose intolerant, but rather intolerant to the A1 beta-casein protein that’s in the most dominant milk on grocery shelves today,” Mroz says. 

Whether you’re plant-milk loyal, dairy-curious, or just tired of post-coffee chaos, this convo cuts through the milk mess and finally makes sense of it all.

What happened to milk (and why your ancestors didn’t have this problem)

Cows, like every other mammal, used to make one kind of milk—simple, digestible, and easy on the gut. Then farmers started chasing profit. “Thousands of years ago, farmers were trying to increase the amount of milk per cow,” Mroz explains. “And as they bred it for industry, there was an economic incentive for them to continue to breed that one specific cow that produced more milk for them.” More milk meant more money, but it also created a genetic mutation that changed the protein structure in milk itself.

“Today, unlike our other mammals of goats and sheeps and humans, we now have two cow milks,” Mroz says. “But a long time ago, we had one.” That “one” was the original A2 beta-casein protein. The newer version, A1 beta-casein, showed up through industrial breeding and became the default in grocery-store dairy. 

The real reason milk messes with your stomach

When your body breaks down A1 milk, it releases a compound called BCM-7—a tiny fragment of protein that can throw your digestion off. Think slower gut movement, bloating, and that ugh feeling after your morning coffee. “A lot of the discomfort doesn’t actually come from the lactose,” Mroz explains. “It comes from this opioid peptide that interacts in a way that causes pain and bloating and gas.” 

Here’s what that means in plain English:

• Lactose is a sugar in milk. Lactose-free products remove that sugar, but they don’t change the protein that’s causing issues.
• BCM-7 acts kind of like a signaling molecule (that’s what “opioid peptide” means). When it builds up in your gut, it can slow digestion and irritate your GI tract.

That’s why switching to lactose-free milk often doesn’t help—you’ve removed the sugar, not the trigger. In fact, some studies show people who think they’re lactose intolerant actually react worse to A1 milk without lactose than to A2 milk that still has it. Cole’s seen it firsthand with his own son, who’s always had a “dairy issue.” Give him a random milkshake and he’s dealing with digestive flare-ups within hours. But with A2 milk? Cole says, “He’s completely fine.”

Why plant milks aren’t saving you

So you switched to oat milk. Or almond. Or soy. And maybe you feel a little better—or maybe not—but at least you’ve escaped the dairy drama, right? Not exactly. Most plant milks come with their own baggage. They’re ultra-processed, loaded with seed oils, and marketed as “clean” when they’re really just engineered to taste like dairy. Mroz found out the hard way. Back in his NFL days, he was pounding up to four protein shakes a day and constantly felt gassy, bloated, and off. “I remember one day looking at the label and thinking, ‘Oh my gosh, this is terrible,’” he says.

At first, he blamed animal protein and switched to plant-based formulas, but the symptoms stayed. “My hypothesis was right that it was the protein causing the discomfort,” he explains. “What I got wrong was that it wasn’t the actual protein, it was that it was A1 protein.” When he switched to A2 dairy, the issues disappeared.

Here’s what most people don’t realize: the seed oils and additives in a lot of popular plant milks—canola, sunflower, safflower—aren’t doing your gut any favors. They’re used to make non-dairy milk taste creamy, but they’re high in omega-6 fats, often extracted with chemicals like hexane, and linked to inflammation when over-consumed. Oat milk’s not off the hook either; testing has found traces of glyphosate (the herbicide in Roundup) in several commercial brands.

What to do if you want to try real dairy again

If you’ve been avoiding milk for years thinking you’re “lactose intolerant,” there’s a good chance you might be fine with A2 dairy, but talk to your doctor before testing that theory. A2 milk is made from cows that naturally produce the A2 protein, like Jerseys and some Holsteins, which means no A1 protein and no BCM-7 mayhem.

It’s pretty easy to find now, too. Most grocery stores (including Target) carry A2 whole milk, 2%, and even chocolate milk. Mroz says once people try it, they usually stick with it because they feel the difference.

When you’re shopping, flip the carton and check the fine print. Look for:

• A2 protein only (it should clearly say “100% A2”).
  
• No carrageenan or seed oils listed in the ingredients.
  
• Short ingredient lists—milk, maybe a pinch of salt, nothing else.

If it reads like a science experiment, skip it. The best A2 milks keep it simple, and that’s kind of the point.

For more insights, tune into The Art of Being Well with Dr. Will Cole wherever you get your podcasts.

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