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Casein Intolerance

Are you prone to stomach cramps or fatigue when you drink milk or eat dairy products? You may have an intolerance to casein – the major protein found in cow’s milk. 

If you’ve had issues with dairy and chalked it up to a generic bad stomach or perhaps an intolerance to something else, it’s possible your body may be struggling to process casein. We’ve put together a guide to identifying, understanding and dealing with casein protein intolerance…

milk and lactose intolerance

What is casein intolerance?

Casein intolerance is a type of dairy intolerance, and may also be called cow’s milk protein intolerance. Casein counts for around 80% of all protein in cow’s milk (along with whey, which accounts for the other 20%. By contrast, human milk contains only 40% casein – which is why our digestive systems often aren’t properly equipped to digest and process it properly. 

A casein intolerance is the body’s IgG reaction to the presence of casein protein. With a casein intolerance, symptoms may be slightly delayed after consumption – in some cases for up to 72 hours. In contrast, casein allergy symptoms will be immediately onset and can be life-threatening.

Casein intolerance symptoms

Because it can take a while for our bodies to digest dairy and casein proteins, it can often be difficult to identify the specific symptoms of an intolerance*. However, some of the most common casein intolerance symptoms include:

stomach pain icon

Stomach ache
Stomach cramps

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Joint pain

food intolerance test

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Easy to use home-to-laboratory test kit

Take our most comprehensive food and drink intolerance* test to find out whether you have an intolerance to 200 food and drink ingredients. Simply take a finger-prick blood sample and return by post for testing. Receive your results within 7 days! No social interaction required.

Optimise your lifestyle with our support, knowing which foods you’re reacting to.

  • Discuss your results with a nutritional therapist. One 30-minute consultation included
  • Measures all four subtypes of food-specific IgG
  • Simple finger-prick blood test
  • Receive expert, accurate analysis from our fully-accredited laboratory technicians
  • Results listed in easy-to-read traffic light values: high, borderline, and normal reactivity
  • Track your progress with a food and drinks diary
  • This test is not available to customers who are pregnant or breastfeeding

Casein intolerance vs lactose intolerance

Because both are found in cow’s milk, casein and lactose intolerance often get confused and conflated. In fact, the two conditions are different.

A casein intolerance is the body’s inflammatory reaction to the casein protein, and its difficulty in breaking it down. If somebody is lactose intolerant, they don’t have enough of the enzyme lactase in their system, and can’t digest lactose (a naturally occurring sugar).

Bread Dairy

 Foods to avoid with a casein intolerance

Although casein intolerance symptoms are not life threatening, they can still be very unpleasant and make life difficult. Once you’ve identified a casein intolerance, some foods to avoid are:

  • Cow’s milk
  • Yoghurt
  • Dairy cream
  • Custard
  • Dairy cheese
  • Protein powder
  • Kefir

Casein-free milk alternatives

Although many of the UK’s favourite dishes and drinks are traditionally made with cow’s milk, these days it’s easy to find dairy-free alternatives that are suitable for those with a casein intolerance. 

If suitable for you, you can experiment substituting dairy milk with these products, or look in the supermarket ‘free from’ aisles for dairy and casein-free products. 

Alternatives for casein intolerance include:

  • Almond milk
  • Soy milk
  • Coconut milk
  • Oat milk
  • Hemp milk
  • Rice milk

Of course, before trying any of these products you should make sure that they’re suitable for your dietary requirements.

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How to test for casein intolerance

Is there a test for casein intolerance? There is – YorkTest’s Premium Food Intolerance Test can pinpoint specific trigger ingredients to identify what you have an intolerance* to. 

The test looks at over 200 ingredients to identify food sensitivities, including cow’s milk, goat’s milk and sheep’s milk. Once you’ve taken the test, you’ll receive your personalised results from our lab team within a week. Included with your test, you’ll also receive a one-on-one consultation with a nutritional expert, who can advise you on the best cow’s milk alternatives and how to manage your diet.


*A food intolerance is defined by YorkTest as a food-specific IgG reaction

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