Dairy Casein Intolerance

Dairy Casein Intolerance FAQ

We are discussing today intolerance, not allergy, and in particular casein dairy intolerance. We are going to take a look at how a casein intolerance is different from a lactose sensitivity, as many people confuse the two and may think they are the same. They are in actuality very different, and we take you on a journey to discover how. We will be looking at what casein is, what it does in the body, what the symptoms of a casein sensitivity are, how diagnosis works and once diagnosed, what you can do about it.

Let’s get started!

So what is a casein intolerance or sensitivity?

Casein is the major protein found in dairy, and it can cause inflammation and immune reactions in people. Whey is the other protein found in dairy, but it doesn’t appear to cause as much immune or intolerance symptoms as it’s relative Casein.

There are different subtypes of casein, and beta-casein is the one that we know the most about through scientific studies. There are 2 specific types of beta-casein, A1 and A2. A1 is the one that has been shown to cause many of the intolerance reactions and symptoms that are associated with a dairy intolerance. In contrast to this, A2 appears to be well tolerated.

Why should you know about Casein?

It’s important that you understand a bit about casein for two reasons:

A) It is the most prevalent protein in cow’s milk. It equates for 80% of all protein found in cow’s milk, with whey making up the other 20 %. In human milk, there is only 40% casein protein, and this tells us that our digestive system isn’t supposed to handle quite so much of it.

B) It has the ability to cause a lot of issues and symptoms. If you are having reactions to it, it’s important to understand why this could be.

There have been many health conditions, disease states and symptoms linked to casein consumption. Here is a short list of some of them:
  • All of the autism spectrum disorders
  • Increased mucus production and difficulties with asthma and breathing issues
  • Coronary issues, including plaque build-up and blockages that can cause stroke etc
  • Sleeping difficulties, including apnoea’s
  • Sudden infant death
  • Blood sugar imbalances and type 2 diabetes
  • Many behavioural issues, particularly in children.

When casein enters the gut, it is digested in a way that causes an opiate-like substance to be released. This can cause some people to be addicted to dairy products. The substance released is called beta-casomorphin-7, and it activates different receptors within the digestive system. Studies have shown that this has released histamine and caused loose stools and stomach pains in the study participants. The same effects were not observed with the consumption of A2 milk proteins. More evidence is still needed in this area for any conclusive answers, but this is a good start in understanding the issues A1 may cause.

IgG and IgA antibodies may also be produced when A1 casein is consumed, which causes inflammation and the different symptoms associated with this. These can range from joint pain to runny nose.

Casein intolerance symptoms?

The symptoms of casein intolerance can be hard to pinpoint on the consumption of dairy, primarily because casein itself is very slow to digest. This means that symptoms may not arise for several days after eating dairy products. The main symptoms that are seen include:

  • Digestive upsets including lots of bloating and abdominal cramps and pain
  • stool abnormalities, diarrhea, constipation, sometimes blood in the stool.
  • Flatulence
  • Runny nose and lots of nasal congestion
  • Adult acne
  • Eczema, other itchy skin rashes
  • Children with behavioural issues/changes
  • Fatigue
  • Unexplained joint pains
  • Mental fatigue, brain fogginess


There can be other symptoms which are specific to individuals and may appear unrelated to the dairy intolerance yet they occur at the same time.

How is lactose intolerance different from casein intolerance?

These two conditions often get confused as being the same thing, yet in reality, they are very different.

Lactose intolerance occurs when someone doesn’t have enough of the lactase enzyme in their digestive system, and therefore cannot digest the milk sugar lactose. When lactase isn’t present in enough quantity, people can get lots of bloating, loose stools, gas and nausea due to a build-up of lactose in the large intestine.

In contrast to this, a casein intolerance is a reaction to the protein component of dairy. The immune system has an inflammatory response and causes the symptoms mentioned above; joint pains, brain fog, behavioural changes, fatigue etc.

How is casein intolerance diagnosed?

To diagnose a casein intolerance there are several test options.

  • An IgG blood test. A sample of your blood is tested against the protein components of various foods, and if antibodies are present this signals an intolerance.
  • There are IgE tests as well, however, these are for allergic responses
  • A food challenge. This is where you remove a particular food for a 30 day period, which would be dairy if you are potentially casein intolerant. After the 30 days, you re-test yourself by consuming some dairy and wait to see if you have any reactions. This type of testing takes a lot of time and can be non.conclusive, however, it can also give some excellent answers.
  • The Intolerance Lab hair test. Our test is very non. invasive, and uses just a few hair strands. We use your hair sample in our biofeedback machine, and it gets tested against over 700 foods and items to discover what your intolerances are. You can order your test HERE.


Are there any risk factors for dairy intolerance?

One of the main risk factors for developing a dairy intolerance is having poor digestive health and function. In particular, existing conditions such as leaky gut, SIBO, IBS, gastritis etc pre.dispose you to developing intolerances. This happens because the gut lining is degraded, and proteins from the foods you eat can escape through and cause inflammatory reactions in your body.

Having an intolerance to gluten may also be a risk factor. The percentage of people with gluten and dairy intolerance is higher than in the general population.

Infantile atopic eczema and being bottle-fed early onare risk factors for developing dairy/casein intolerance in babies. This also appears to be more common in those with relatives who also experience dairy intolerance.

Foods to avoid for the casein sensitivity.

Casein is found in high protein dairy foods, and so these are the specific foods you need to avoid. They include:

Diary milks – full fat, low fat, etc

Diary yogurts – all

Deserts such as custards made from dairy

Dairy cheeses


Whey and casein rich protein powders

The lesser protein dairy foods include butter and cream, and they have only small trace amounts of casein. However, if you are highly casein sensitive it is still best to avoid these as well. If your intolerance is mild, you may be able to tolerate a small amount of butter or cream.

Casein intolerance, foods to enjoy.

As far as a casein intolerance goes, most, if not all cow’s milk dairy needs to be removed from your diet. However if your intolerance is only mild, and if it is specific to the A1 casein, then you may be able to enjoy some A2 milk products. The best thing to do is to try them for yourself, and see how you react.

Ghee may be another option for you, as it has zero casein in it. Again, try some and assess how your body reacts.

Is there a cure for casein intolerance?

No there isn’t. Like all food intolerances, there are no cures. However, you can manage your condition well by removing all sources of high protein dairy from your diet.

What’s the best way to manage a casein intolerance?

The best thing you can doto manage a casein intolerance well is to remove all dairy from your diet, specifically the high protein dairy sources listed above, and any products made from dairy such as ice cream etc.

If your intolerance is caused by poor digestive health or an existing digestive condition such as IBS or leaky gut, seeking help to remedy your condition may also help to heal your intolerance. A Naturopath or holist Nutritionist are well-positioned to help you with this.

Do the symptoms of dairy/casein intolerance last a long time?

Casein is slow to digest, and so the symptoms can take 2 to 3 days to manifest. They don’t last a long time after that, usually only 3 to 5 days. However, if you keep eating dairy you may have the symptoms constantly.

Can I be intolerant to the fat found in milk?

Milk fat isn’t generally an issue where intolerances are concerned. There is no proof that this affects someone with casein or lactose intolerance. However, you may have issues with the way your body digests fats in general, which can cause symptoms such as nausea, stools that float and abdominal cramps.

Are brain fog and stomach pains a sign of casein intolerance?

Yes, they absolutely can be. When you eat casein it causes inflammation to occur, which is what causes these symptoms.

Can I become intolerant to dairy overnight?

It can seem like this happens, however, it is a long term process that occurs in your body. Over time your gut gets degraded by things like foods, medications, tap water and also stress. You can develop conditions such as leaky gut or IBS, which then degrades your gut lining and paves the way for food intolerances to show up. Although it seems like you just woke up with it one day, it’s a long term scenario. Working with a holistic healthcare provider will allow you to heal your digestive tract and potentially eat dairy without issues again.

Is dairy bad for my gut?

This question depends on the health of your gut. If it is in bad shape as discussed above, then dairy can certainly cause issues.

However, dairy food is a highly nutrient-rich food source and isn’t bad for you if your digestive tract is healthy and you don’t have intolerances or allergies to it.


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  3. Sodhi, M., Mukesh, M., Kataria, R. S., Mishra, B. P., &Joshii, B. K. (2012). Milk proteins and human health: A1/A2 milk hypothesis. Indian J Endocrinol Metab, 16(5), 856.
  4. Vesa TH1, Lember M, Korpela R. (1997) Milk fat does not affect the symptoms of lactose intolerance. Eur J clin Nutr 51(9), 633-6
  5. Walker-Smith, J.A.(1992) Cow milk-sensitive enteropathy: Predisposing factors and treatment. The Journal of Pediatrics, 121:5, S111 – S115

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