Casein intolerance and casein-free diet

Casein intolerance and casein-free diet

Today we’re looking at casein intolerance and how to follow a casein-free diet. We’ll explore the difference between casein and lactose, how to tell if you’re casein intolerant, what tests are used to determine intolerance, and how to avoid casein in your diet.

Casein vs lactose intolerance

With an increasing awareness of cow’s milk and dairy intolerances, there is much talk about one particular type of intolerance: that is, lactose intolerance. This is an intolerance to the sugar, lactose found in milk.


Lactose intolerance is one of the most common food intolerances, so it’s no wonder that this food reaction is getting attention. However, intolerance to casein – the protein in dairy – should not be overlooked. It can cause similar symptoms to lactose intolerance and is a common cause of intolerance and allergy. It’s also important to note that having lactose-free milk does not change the casein in the milk. So if you’re reacting to dairy, it may be the casein that’s the problem!

What is casein?

Dairy is made up of two milk proteins – casein and whey. Casein is the more dominant protein and accounts for about 82% of the protein in cow’s milk. The remaining 18% is serum and whey protein.

The above figures may make it sound like there’s much protein in milk, but in fact, the casein makes up less than 3% of the total volume of milk. This can, however, be enough to trigger both casein intolerance or casein allergy. Having full-fat or skim milk does not change the protein content of the milk, and as we discussed, lactose-free milk still has the casein in it as well.

Of the different types of milk: sheep, buffalo and cow’s milk have the most significant amount of casein. In contrast, human breast milk has the lowest. Because casein is a protein, it is present in even greater amounts in dairy products with a higher protein concentration – such as cheese, yoghurt, and kefir.

What are the symptoms of casein intolerance?

If you are intolerant to casein, it can take a few days for the symptoms to appear. The symptoms of casein intolerance can include:

  • bloating
  • abdominal discomfort
  • increased gas/flatulence
  • diarrhoea and/or constipation
  • skin rashes (like eczema)
  • acne
  • nasal congestion or runny nose
  • joint aches
  • tiredness 
  • mental fatigue or brain fog

Like other forms of intolerance, the symptoms vary from person to person, and they can worsen the more casein you consume.

Testing for casein intolerance

There are two main ways to test for casein intolerance: a food challenge and a food intolerance test. The food challenge involves avoiding casein for a period of 30 days and reintroducing it to see if you’re reacting to it. A food challenge must be done under the guidance of a practitioner (like a dietician, nutritionist, or naturopath) to ensure you do it correctly and avoid nutrient deficiencies. 

Another way to test for casein intolerance is a food intolerance test. Our hair test is a quick way to check if you’re intolerant to casein, as well as over 350 other foods. The test looks at 700 food and non-food triggers that you could be reacting to and gives you the results within 3 days of our lab receiving your sample. To do the test, click HERE and send us a sample of your hair.

Casein-free diet

All dairy – including products made from cow, buffalo, goat, and sheep milk – contain the casein protein to varying degrees. In order to follow a casein-free diet, it is essential to avoid all foods made from dairy including:

  • all forms of dairy milk (including full cream, skim, low-fat, buttermilk, evaporated, and lactose-free milk)
  • cheese, rennet and curd
  • butter and margarine 
  • yoghurt
  • kefir
  • cream (including sour cream, heavy cream, whipped cream, and crème fraiche)
  • custard
  • ice-cream
  • milk solids or protein powder (called hydrolyzed casein or casein hydrolysate)
  • food preservatives: sodium or calcium caseinate
  • wine (when casein is used as a fining agent)
  • dental materials for tooth remineralisation (called CPP–ACP, which stands for casein phosphopeptide–amorphous calcium phosphate)

Casein is used in various foods as a food additive: either as sodium caseinate or calcium caseinate. These food additives are used to increase the shelf-life of processed foods and can be found in products like creamers, some baked goods, ice cream, whipped toppings, cheeses, pasta, and meats. 

Wine may pose risks for Casein Allergy

If you are very intolerant or allergic to casein, it is also essential to know that milk or casein is used as a fining agent to make wines. Some wineries use fining agents to remove suspended impurities or materials in wine and make it look less ‘cloudy’. They can also be used to remove tannins and reduce the astringency of wines. While this process can produce more palatable wine at a faster and greater scale, it also removes resveratrol – which is a polyphenol (an antioxidant) that imparts some of the health benefits associated with occasional wine consumption.

If you need to follow a casein-free diet, it is beneficial to work with an experienced practitioner who can help you avoid casein while eating a nutritionally complete diet. A trained practitioner, like our nutritionists and naturopaths, will assist you with a diet plan so you can make the best dietary choices for you.

Part of your diet plan may be choosing dairy alternatives that meet your nutritional needs. Dairy milk alternatives include:

  • Soy milk
  • Nut milk (almond, macadamia, cashew)
  • Coconut milk
  • Rice milk
  • Oat milk

There are also alternatives for dairy products like butter, cheese, chocolate, and ice cream.


Today we’ve talked all about casein intolerance. We learnt that casein is the main protein in dairy and that intolerance can lead to symptoms like digestive upset, skin rashes, sinus issues, and fatigue. We looked at the two main ways that you can test for casein intolerance. These are a food challenge (careful elimination and reintroduction of dairy) and a food intolerance test like our hair test. We then explored the various foods to avoid if you are intolerant to casein, and we discussed some food alternatives that you can try under the guidance of your practitioner.

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