For over 16 weeks I removed cow-milk dairy entirely. The results surprised me. My fatigue lifted. The heavy feeling in my head cleared. My tummy became calmer – fewer flatulent episodes, and fewer “gatherings” of mucus stuck at the back of my nose.
Then I re-introduced cow dairy (9 days) and almost all the symptoms returned: the taste of “snot” at the back of my nose; backed-up bowels; flatulence again.
On the other hand, I tolerate goat and sheep dairy – and even a daily cup of tea made with A2 Guernsey milk – without any reaction at all.
That pattern – dairy from cow = trouble; dairy from sheep, goat, or A2-cow = fine – pushed me to dig into the research. Because I suspect I’m part of that group between classic lactose intolerance and full-blown allergy.
Here’s what I found, and why I think the science still hasn’t caught up with what many of us are actually living.
Setting the scene: What do we mean by “dairy intolerance”?
When people talk about being “dairy intolerant,” they usually mean lactose intolerance. But that’s just one piece of the puzzle. From a clinical perspective, there are at least two broad types of dairy reactions.
- Lactose intolerance – This happens when your body doesn’t produce enough of the enzyme lactase, which breaks down lactose (the sugar in milk). Undigested lactose ferments in the gut, creating gas, bloating, and sometimes diarrhoea. It’s not an immune reaction – it’s a digestive one.
- Milk-protein reactions – This is where the immune system becomes involved. It includes both IgE-mediated allergies (like hives or wheezing after milk) and slower, non-IgE-mediated responses that mainly affect the gut. These can cause inflammation, altered absorption, and ongoing discomfort.
My symptoms don’t fit neatly into either of those boxes. There’s no rash, no vomiting – but there is gut chaos, fatigue, mucus, and brain fog.
So, what’s happening?
What the research says
The science around milk-protein differences has become much more interesting recently, especially when it comes to the two main types of casein protein – A1 and A2.
A1 beta-casein (found in most supermarket cow milk) breaks down in the gut into a peptide called beta-casomorphin-7 (BCM-7). Studies suggest BCM-7 may slow gut transit, influence inflammation, and even affect the gut–brain axis – the communication network between your digestive system, immune function, and emotional state.
A2 beta-casein (found in goat, sheep, Jersey, and Guernsey milk) breaks down differently and doesn’t produce BCM-7. That difference may explain why some people, like me, can tolerate goat, sheep, or A2 milk but struggle with standard cow milk.
In several small studies, people who believed they were lactose intolerant found they could drink A2 milk without symptoms – yet reacted to regular A1 milk. That suggests their discomfort wasn’t caused by lactose, but by the protein type and its downstream effects in the gut.
While the research is still developing, it points toward something more nuanced than “lactose intolerance” or “allergy.” For some of us, it’s about how our body interprets and reacts to the proteins in milk — and that interpretation can ripple through digestion, energy, and even mood.
How my experience fits (and doesn’t quite fit) with the research
When I line up my real-life experience next to what the research says, things start to make sense – but not completely.
I can eat goat and sheep dairy with no problem. Those tend to have an A2-like protein structure – gentler on digestion for many people.
I can even enjoy a splash of A2 Guernsey milk in my tea every day without a single symptom.
But give me regular cow’s milk, and within a few days I’m bloated, gassy, foggy-headed, and constantly clearing my throat from the mucus gathering at the back of my nose.
So what’s going on here?
It looks like my body can handle A2 proteins easily, but reacts to the A1 type found in most standard cow’s milk. It’s as if my gut and immune system see A1 milk protein as an irritant – not enough to cause a full allergic reaction, but enough to set off inflammation, slow digestion, and leave me feeling congested and foggy.
That would mean my sensitivity isn’t really about lactose at all – it’s more about the protein profile. It’s probably not an “allergy” in the traditional sense, but something sitting in that murky middle ground between intolerance and immune response.
And maybe that’s exactly what the research hasn’t quite caught up with yet. Most studies focus on either severe milk allergy or straightforward lactose intolerance. But what about people like me – those who don’t react dramatically, yet feel unmistakably unwell after A1 cow’s milk?
Where the research still hasn’t caught up
This is where I think the science still needs to evolve.
The studies comparing A1 and A2 proteins in humans are still quite small and short. Most look only at digestion – gas, bloating, stool consistency – but rarely explore what happens beyond the gut, like mucus build-up, fatigue, or brain fog.
And while we do have some fascinating theories about how A1 milk breaks down into a peptide called BCM-7 (which may affect gut motility, inflammation, and even mood), the evidence in humans is still early and patchy.
Most importantly, researchers rarely account for individual context. Our microbiomes, immune histories, trauma backgrounds, and nervous-system states all change how we react to food. A “one-size-fits-all” view of dairy intolerance just doesn’t work – and trauma-informed science would recognise that.
So for now, people like me – and maybe you – are living in that “in-between” space that medicine doesn’t fully understand yet. But that doesn’t make the experience any less real.
The bigger picture: microbiome, immune history, and nervous system
Emerging science shows the story is far richer than “enzyme yes/no” or “allergy yes/no.”
Your gut microbial community, your immune system’s history of what it’s tolerated (or not), and even your nervous system’s state all influence how your body reacts to food. In other words, two people can eat the exact same meal and have completely different outcomes – because their internal context is different.
For example, studies show that people with disrupted gut microbiomes are more prone to food sensitivities and inflammatory responses. Other research links trauma and chronic stress to changes in gut microbiota and immune regulation, affecting how we digest and tolerate certain foods.
What this means in practice
If there’s one thing my body has taught me, it’s this: listen closely. The feedback is there.
When I have standard cow dairy, I feel it – bloating, brain fog, mucus, fatigue.
When I stick with goat, sheep, or A2 milk, I feel clear, light, energised. That’s my data.
So here’s what I’ve learned to do:
Trust my experience. My body gives me clear signals – I just had to start believing them.
Track with curiosity, not control. I mentally track what I eat and how I feel – gut, head, mood, sinuses – I need data!
Choose what nourishes, not what triggers. Goat, sheep, and A2 milk give me calcium and protein without chaos. That’s balance, not restriction.
Support the whole system. The gut doesn’t work in isolation. Sleep, stress, movement, and emotional safety all help my digestion regulate.
A gentle reflection
Maybe you’re reading this and recognising yourself – that mix of gut discomfort, brain fog, and post-nasal congestion that never quite made sense.
If so, you’re not imagining it. You’re simply noticing something the research hasn’t learned to measure yet. And that’s how science moves forward: one lived experience at a time.
Closing thought
Your experience matters. It challenges the narrow definitions of dairy intolerance and points to a more nuanced, embodied understanding – where dairy proteins, gut-immune interactions, and nervous-system regulation all meet.
You’re not alone in feeling like there’s “something there” that the typical categories don’t explain. And as more people share stories like this, maybe the science will begin to catch up.
Until then, trust your body’s data, stay curious, and keep compassion at the centre of every change you make.
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