“DAIRY IS SO BAD FOR YOU!!!!” Says everyone with endo. So we toss dairy and indeed we do feel better without it, or we don’t notice a difference, or it doesn’t seem to make a difference one way or another (so we keep eating it), or, or or….. what gives? And why are we told it’s bad for endo, specifically? What’s the science to back this up? To try to answer these questions, I did a lot of digging around on PubMed (read: published scientific literature) to see what I could find on dairy and endometriosis to help explain why - oh why - it affects some of us so poorly, and others not much.

But First, Why Dairy Is Great If You Can Tolerate It

Dairy products on the whole are very nutritious if they’re

Properly sourced,
Minimally processed, and
The body consuming them tolerates dairy.

When these three points line up, dairy becomes an incredible source of calcium, iodine, vitamin A, D, K2, and B vitamins. What the dairy animals are eating makes even more of a difference in nutrition. 100% grass-fed dairy has 25% more omega 3’s, 500% more of the anti-inflammatory fatty acid CLA, and more antioxidants, Vitamin A, and K2 than conventional dairy (1, 2). Raw milk offers an additional boost of probiotics and enzymes. Fermented dairy offers a smorgasbord of probiotics that can help aid the gut microbial communities, and consumption of fermented dairy has been observed to lessen certain inflammatory markers and increase certain beneficial microbes within the intestinal tract (3, 4). Pretty cool.

This is why many cultures historically have consumed large amounts of dairy without chronic disease. It was a nutritious food for them.

The problem is today that these three factors rarely line up, meaning when we modern-folk eat dairy we may experience symptoms from minor inconveniences to serious reactions, especially in the endo-realm. What’s the reason? After scouring PubMed I found 4 potential issues with dairy and endo, some that may relate to you and your body, or not! Check them out to see if any of these issues resonate:

1) Endometriosis and Dairy: A1 Casein is The Biggie

Casein is a protein in milk, and there are two types: A1 and A2. A1 casein is mainly from Holstein and Friesian cows (the primary cows used for dairy operations in North America, the UK, and Australia), meaning if you go to the store and buy regular ‘ol dairy products, they’re full of A1. Bummer, because when it comes to many of the worst inflammatory symptoms of dairy we hear about, A1 is the biggest culprit. Like, really. By far.

The problem with A1 casein is that, for many people, the body turns it into a product called casomorphin. Casomorphin is an opioid-like substance that can cross the intestinal barrier and enter your circulation, here stimulating the immune system (5). Since endometriosis is known as a systemic inflammatory condition, much of it triggered by overactive immunity, increased triggering of the immune system is simply not what your body needs. An overactive immune response triggering substantial inflammation can lead to all kinds of inflammation-based symptoms such as migraines, joint pain, insomnia, headaches, aches and pains, fatigue, and even menstrual pain. Many of these symptoms overlap with endo, obviously, and why some women feel incredible removing dairy.

endometriosis diet endo diet — A1 casein is associated with chronic inflammation rather than digestive issues. This means if you’re reacting to A1 you may have chronic pain, migraines, endo flairs, joint pain, allergies, etc, rather than bloating and a stomach ache.

Casomorphin is also a potent histamine liberator (6)- something directly tied to endometriosis pain and many endometriosis-related symptoms. Histamines are a part of a normal immune response to allergenic triggers, why you’re recommended to take a histamine blocker if you’re head is swollen, inflamed, and itchy with pollen allergies. The problem is that endometriosis lesions have more mast cells in them than normal tissue, mast cells being those which produce histamines, meaning consumption of A1 dairy may cause the endo in your pelvis to inflame and react in a similar way as your sinuses during ragweed season: insert painful endo flare.

Interestingly enough, A1 dairy also appears to reduce glutathione levels, leaving you more susceptible to free radical damage (7). Glutathione is your master antioxidant, one your body should be making a lot of to fight the cascade of free radicals and inflammation coursing through your body. If you want to better detoxify, lower inflammation, and calm the fire - A1 may be reversing that hope.

Casomorphin doesn’t affect everyone so negatively, but it does seem to be especially harmful to those who can’t break it down in the intestinal tract (due to dysbiosis) and those who have leaky gut (8). Sadly for us endo girls, there’s a high probability we suffer from both, rendering us more susceptible to A1 damage and inflammation.

A2 casein is different. It’s found in dairy products derived from other animals such as goat, sheep, camel, and certain cow breeds such as Jersey, Guernsey, and most Asian and African breeds. And, lucky for us, A2 dairy doesn’t appear to have the same negative inflammation-producing effects as A1 (YAY!!!!).

A2 is not associated with triggering immune overreactions or histamine liberation, and in a comparative analysis was shown not to have the gut-related inflammatory response that occurred within the A1 group (1). A2 may even be beneficial to your antioxidant systems since A2 consumption has been shown to significantly increase glutathione levels, potentially offering a protective effect against the free radical cascades associated with endo (9).

In all, A2 casein is an entirely different beast than A1, proving to offer anti-inflammatory benefits instead of a pro-inflammatory, immune, and histamine stimulating product from A1. Unfortunately, you can’t test for reactions to A1 casein since it’s not an allergy, but because of the vast difference between A1 and A2 dairy, women who think they are allergic to dairy may actually be able to tolerate A2 just fine, and another great example of how not all dairy is created equal.

2) Endometriosis and Dairy Intolerance: Let’s Talk Lactose Intolerance

Lactose intolerance is an important consideration since any intolerance will lead to low-grade inflammation (adding to the inflammation bucket we have that over-floweth), plus it may be a PRIME contributor to endo-belly. Indeed lactose indigestion is often associated with gas, bloating, diarrhea, constipation, and indigestion.

Lactose is a sugar found exclusively in milk, one which requires an enzyme called lactase in order to digest. We are born with lactase in our guts to help us process dairy as babies, but much of our levels drop as we get older, especially those of us with darker skins (i.e. ancestry that didn’t eat a profuse amount of dairy like Swiss milkmaids, French cheesemakers, or British butter lovers).

Because lactose is a sugar, it can be eaten up by fermenting bacteria or removed by singling out the butterfat. This is why women who are lactose intolerant may be able to tolerate fermented yogurt and butter, but not milk and ice cream. But if you have big-time digestive issues, and are still eating dairy, consider a one-month boot to see if your symptoms improve.

3) Endometriosis and Celiac: The Dairy Connection

Celiac disease is a sister disease to endo, meaning some of us have both diseases. Fun! And if you have celiac, you should be aware of the potential cross-reactivity of dairy with gluten, meaning your body may react to dairy in the same way you react to gluten. This was demonstrated in a study that saw 1/2 of celiac patients had the exact same inflammatory response in the gut mucosal lining when eating dairy as they did when eating gluten.(10) This helps makes sense why some folk with celiac may still have digestive issues after removing gluten because dairy is still damaging their intestinal lining

4) Hormones and Chemicals in Conventional Dairy

A recent study analyzing organic versus conventionally produced milk found that nearly all conventional milk was contaminated with some level of pesticide, growth hormones, or antibiotics (11). Antibiotic residues were found in 60% of conventional milk samples (including sulfamethazine and sulfathiazole, both outlawed for use in milk production) while none were found in the organic samples. Pesticide residues were also found in 60% of conventional milk samples while none were found in the organic, while the average amount of bovine growth hormones were 20x higher in the conventional than the organic.

So if you're consuming a lot of conventional dairy and feeling junk, you may want to consider your sourcing. If you do choose to dabble with dairy, organic and 100% grass-fed dairy options are your best bet by far!.

Understanding Your Unique Tolerance

Because there are so many gray areas, the best way to understand your own tolerance for dairy is by cutting it totally out for 1-3 months to see how you feel. Some people with endo will feel a life-changing shift, while others may see subtle changes. Follow your digestive changes as well as changes within your menstrual cycle and pain, since any symptoms may be associated with dairy consumption. After that time, reintroduce foods one by one (starting with the least likely to trigger you, per below) to see how you tolerate them. Start with:

Ghee or Butter. If no reaction after a week, then consider…
Kefir or Yogurt. If no reaction after a week, then consider…
Goat or Sheep Cheese. If no reaction after a week, then consider…
A2 Raw milk (only if you prefer and/or feel safe). If no reaction after a week, then consider…
A2 Cow Cheese. If no reaction after a week, then consider…
A2 Pasteurized milk, ice cream. (Yes this can take a while to introduce line item by line item. Remember the goal though, being able to eat the dairy you can tolerate!! If you like dairy, and want to eat it, it’s worth the time commitment to know what you can eat without problems, and what’s best avoided.)

Also, consider sourcing as an important component. Avoid dairy produced by conventionally raised animals that may have some toxic byproducts, and look for 100% grass-fed animals for a boost in nutrition!

FAQ

When can I introduce A1 diary? To be honest, I don’t recommend A1 milk, yogurt, or cheeses to anyone that has bad endometriosis symptoms, or inflammatory issues (although, to be fair, if you’re eating ghee or butter it doesn't seem to matter much if you consume A1 or A2). Instead look for goat, sheep, or milk advertised as A2 - which is becoming more common as A1 reactions skyrocket. But, if you really want to get back on A1 and feel better, give it a whirl! For sourcing, aim to find 100% grass-fed dairy first, organic second, and conventionally produced as a last resort.

What if I can’t afford/find organic or grass-fed? For anyone with food access barriers or financial issues who can only find/afford conventional A1 dairy (and who has active endometriosis), it may be best that you simply avoid it. The science is simply too clear on the damage it can provoke in susceptible individuals.

I can’t tolerate ANY dairy, what should I do? If you can’t tolerate dairy at all, that’s okay! Just make it a true focus to get dairy-based nutrients elsewhere since it’s easy to let calcium intake slide if you’re not diligent on proper substitutions such as dark leafy greens (why I recommend 3 cups cooked greens/day), bone-in fish, and certain nuts and seeds.