Gluten and Casein

plate with goat cheddar, goat cheese on a cracker, apple.  Glass of milk top left.

Gluten and Casein: You’ve been on a gluten free diet for a while now but things aren’t really much better.  You still feel bloated much of the time and the bathroom situation is, well, messy…still.  Are you frustrated?  Of course you are, but you are not alone.  About 30% of people with celiac disease find their symptoms do not resolve when they remove gluten from their diet1.  What then could be the problem?

First of all, you need to consider cross-contamination.  Is it possible that you are still getting gluten from somewhere?  Crumbs on the counter?  Someone double dipping into your peanut butter? 

Gluten and Casein: If you’re pretty certain you’re not ingesting gluten, then you need to look elsewhere.  It is very common for people with celiac disease to also suffer from other food intolerances, and the most prevalent of these is dairy.  Milk has two components that are likely to cause issues.  The first and most common is lactose, the sugar in milk.  The second is casein.  

Skip right to the section that interests you or read through to learn all about gluten and casein

What is casein?

Milk, like all foods, can be broken down into it's three macro-nutrients: carbohydrate, protein and fat.  Lactose, which is the sugar in milk comes under the carbohydrate category.  Casein is one of the many proteins in milk.  The other main one is whey.  Both of these have the potential to cause allergies or intolerances, but the more common one is casein.  Casein is the part of the milk that curdles to make cheese.  

Why is casein a problem?

There may be a couple of things going on.  First of all, not all casein is created equal and there are a few varieties that may not be well tolerated by humans.  The main one is alpha S1 casein2 which is most prevalent in bovine (cows) milk.  Milk from other types of mammals have casein as well but they have lower percentages for alpha S1.  We’ll get into that a little later.

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Casein allergy or casein intolerance is a condition all on its own, unrelated to celiac disease.  Up to 3 percent of children under the age of three have issues with cows milk3.  This often surfaces in infancy as these children can’t digest formula made from cow’s milk.  In these cases, assuming breast feeding is not an option, formula from other sources such as soy is usually the solution.  There is some conjecture that even in these cases, this casein intolerance may be a pre-cursor or even a trigger to celiac disease in some of these children.  Research is still ongoing.

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When it comes to casein intolerance in people with celiac disease, the cause that is most under investigation now is a phenomenon called “cross-reactivity”, specifically between gluten and casein.  There is not a lot of research on this yet but it’s gaining some ground, so keep an eye.  I certainly will and will provide updates as new info comes along.  Cross reactivity essentially means that a certain substance “mimics” another substance in its effect on the immune system.  In the case of gluten and casein cross-reactivity, it may be that the cross reactive protein, in this case casein, “looks” a lot like the primary reactive protein, gluten.  The two may be similar in structure so the immune system reacts in a similar way.  For those of us with celiac disease, we have an auto-immune response to gluten and perhaps other proteins such as casein are causing a similar auto-immune reaction.  Another example of a food protein that may be cross reactive to gluten is avenalin, from oats.  That’s why so many people with celiac can’t tolerate even gluten free oats.

The chart below is taken from a laboratory study that shows cross reactivity of several different food proteins with α-gliadin or gluten.  Gluten and casein is the most prevalent4

bar graph showing cross reactivity with gluten and other proteins.  Casein is the highest.

A Few Facts:

If you like to geek out on this stuff like I do, here are some interesting facts:

  • Baking “denatures” the protein so some people can tolerate milk in baked goods but not in raw or fluid form.
  • Pasteurization does not heat the milk for long enough or at the right pH to denature the protein.
  • Milk from different mammals have different casein profiles, so some people who can’t tolerate cows milk are fine with goat, sheep or water buffalo milk.
  • One study showed about 50% of celiac patients tested had a reaction to casein that was similar to gluten.  This was compared to zero in the control group5.  This seems to indicate a correlation between gluten and casein reactivity.

Lactose or casein, how can I tell?

To find out if you are allergic to casein or another component of milk, you can go to an allergist and have a skin prick test.  However, for most folks looking for a relationship between gluten and casein, the issue is more of an intolerance than an allergy and there is no test for that.  The only way to know if you have an intolerance to any food is to eliminate it from your diet and see if you feel better.  If you cut out milk and find that your symptoms improve, then you’ve narrowed the problem down to dairy, that’s a start.  To figure out if your issue is lactose or casein, you’ll need to look for a few more clues.  I suggest first reading the article on lactose intolerance, then come back here.  I’ll wait.

One of the things you learned about lactose is that there are dairy products that are well tolerated by folks with lactose intolerance such as, lactose free milk and ice cream, yogurt and hard cheeses.  If you don’t tolerate these foods, then that’s a good clue that your issue is casein rather than lactose.  Another clue is if you have been gluten free for six months to a year and still can’t tolerate dairy products.  Secondary lactose intolerance from celiac disease usually improves once a gluten free diet is established and the gut starts to heal.

Sheep and Goats and Other Mammals

Photo by Strvnge Films on Unsplash

All mammals produce milk for their young.  It’s actually part of the definition of a mammal.  We are the only mammal that drinks milk from other mammals.  Cows are the biggest source of milk for humans in North America.  However, in other parts of the world consumption of goat and sheep milk is more prevalent and that is making its way to North America, mostly in the form cheese.  Water buffalo is another mammal who’s milk is made into cheese. 

A1 Beta Casein vs A2 Beta Casein

Many people who cannot tolerate cows milk find that these other milks and cheeses are okay.  Why is that?  The science is fairly new on this so I couldn’t find a whole lot that is conclusive, but is seems to center around the prevalence of A1 beta casein, vs A2 beta casein.  This kind of makes sense as cows milk is higher in the A1 variety and sheep, goat and water buffalo milk are lower in A1 and higher in A2.  This has caused some stir in the scientific community and has even caused some groups to start to advocate for consumption of milk from certain breeds of cows that is higher in A2 beta casein.  Beware however as the science is far from conclusive and there may be more marketing to this than fact.6  At the end of the day my best recommendation is to listen to your body.  Try some alternatives and if they work for you then go with that.  If not then you have your answer.  

Gluten and Casein: What can you do about it?

As with gluten, the only way to deal with a casein intolerance is to avoid the source, in this case, dairy products.  Lucky for those of us who deal with this, there are a lot of options out there.  Plant based milks like coconut, almond, soy etc are highly available and substitute just fine in cooking, baking and to pour on your cereal.  Vegan "cheese" is also available and tastes pretty good.  Of course it's a bit less "natural" so you need to decide if it's right for you.

If you're one of the lucky ones like me who can tolerate sheep and goat’s milk then your options are wider.  The best thing about these alternative milks and cheeses, besides the taste, is the nutritional profile.  You are still getting all of the nutrients from milk without the pain.

Does Goat and Sheep Cheese Have Casein?

Yes, you read above, goat and sheep milk both have casein but they are higher in A2 beta casein and lower in A1 beta casein which is more prevalent in cows milk.  This is why a lot of people who can't tolerate cow's milk or cheese made from cows milk can have milk and cheeses from goats, sheep and even water buffalo.  

zucchini lasagna made with goat cheese and vegan cheeses shreds.Zucchini lasagna made with goat cheese and vegan cheeses shreds.

Cheese made from these alternatives are great tasting, widely available and the variety is increasing all the time.  I love nice sharp goat cheddar on grilled cheese, or goat mozzarella on pizza ore lasagna.  Soft goat cheeses come plain or garnished with herbs or cranberries.  These make cheese sauces smooth and creamy or simply top off a gluten free cracker.   Pecorino Romano from sheep’s milk is a lovely hard cheese that substitutes nicely for parmesan.

Go here for a whole list of dairy substitutes.

A Note About Feta Cheese

greek salad topped with feta cheese with a glass of rose wine on the left.Photo by Loes Klinker - Unsplash

True feta cheese is made from sheep or goats’ milk , so if you can tolerate these you're good to go.  However,  some feta cheese is made with cows milk so you need to check the label.  If you're ordering Greek salad in a restaurant or any other dish made with feta cheese be sure to ask if it's goat or sheep feta.  Many restaurants will buy the cow's milk feta because it's cheaper.


Key Points to Remember

  • If your gluten free diet has not resolved all your symptoms, first look for cross contamination, then consider other food intolerances
  • Dairy is the most common food intolerance that correlates with gluten.  First consider lactose intolerance.  If that's not it then it could be a gluten and casein cross-reactivity.
  • The only way to treat a casein intolerance is to avoid cows milk.
  • Milk from other mammals also has casein but some people can tolerate these.  The only way to know is to try.

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Celiac and Dairy: Lactose Intolerance

Similar to gluten and casein, gluten and lactose also go hand in hand to cause tummy trouble for those of us with celiac disease. 

Celiac and Other Food Intolerances:  Yes it's possible.  In fact it's very common for people with celiac disease to experience other food intolerances as well.  Go here to find out the most common ones and how to figure it out. 



1. Vojdani, A., & Igal, T. (2013). Cross-Reaction between Gliadin and Different Food and Tissue Antigens. Food and Nutrition Sciences4, 20–23.,2013.41005

2. Stout, J., MS. (2019, March 12). Is Goat Milk Gluten Free? Retrieved April 23, 2021, from https//

3. Demarco, P.,MD and Lupoli, T.,DO (2020). Milk Allergies: Understanding Milk Allergy Symptoms and Treatments. Retrieved April 23, 2021, from https//

4. Vojdani, A., & Igal, T. (2013). Cross-Reaction between Gliadin and Different Food and Tissue Antigens. Food and Nutrition Sciences, 4, 20–23.,2013.41005

 5. Vojdani, A., & Igal, T. (2013). Cross-Reaction between Gliadin and Different Food and Tissue Antigens. Food and Nutrition Sciences4, 20–23.,2013.41005


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