Dairy Intolerance (Lactose, Casein, and Whey)

Having a food intolerance is not fun.  It can cause abdominal pain, discomfort and nausea.  It also causes embarrassing symptoms like flatulence and diarrhoea.  Other symptoms linked to food intolerances include muscle or joint pain, headaches, exhaustion and even skin symptoms like rashes and eczema.

Dairy is just one of those foods that many people seem to be intolerant of.  Let’s talk about the main components of milk that people react to: lactose, casein and whey.

Milk sugar (lactose) intolerance

It’s estimated that up to 75% of adults are lactose intolerant.  Lactose is the carbohydrate ‘milk sugar’ naturally found in most dairy products.  Lactose intolerance is so common you can buy lactose-free milk in your regular grocery store.  Lactose-free products are treated with the enzyme ‘lactase’ that breaks the lactose down before you ingest it.  It’s this lactase enzyme that is lacking in most people who are lactose intolerant.

The lactase enzyme is naturally released from your intestine as one of your digestive enzymes.  It breaks down the lactose sugar in the gut.  When someone doesn’t have enough lactase, the lactose doesn’t get broken down the way it should.  Undigested lactose ends up being food for the resident gut microbes.  As they ferment the lactose, they create gases that cause bloating, flatulence, pain and sometimes diarrhoea.

Lactose is in dairy but is in lower amounts in fermented dairy (eg. cheese & yogurt) and butter. Steering clear of lactose isn’t that easy as it is added to other foods like baked goods, soups and sauces.  If you are taking any medications or supplements, check to see if it is in there too, as lactose is a common ingredient in them.

If you have symptoms of lactose intolerance, keep an eye on food, medication and supplement labels.

Milk protein (casein & whey) allergy

Milk is a known and common food allergen.

So, what are the allergens in milk?  You have heard of ‘curds and whey’?  Well, these are the two main proteins in milk.  The solid bits are the curds (made of casein) and the liquid is the dissolved whey.

Unlike lactose intolerance, casein and whey can cause an actual immune response.  It’s an allergy. This immune response can cause inflammation. In fact, we don’t know how many people have these milk allergies, but most estimates put it far below that of lactose intolerance.

Like lactose, these allergenic milk proteins can be found in other products too. They are not just in dairy but are often in protein powders as well (have you heard of ‘whey’ protein powders?).

Some of the symptoms of milk protein allergy differ from that of lactose intolerance; things like nasal congestion and mucus (phlegm) are more common here.  Casein seems to be linked with belly fat.

Interestingly, people who have gluten intolerance are often allergic to milk proteins like whey and casein as well.  These can go hand-in-hand.

Like lactose intolerance, if you are allergic to casein and whey keep an eye on labels so you can avoid these.


If you get gassy, bloated, or diarrhoea after eating dairy, you may have a lactose intolerance. If you often get a stuffy nose and mucus, then you may be allergic to casein and/or whey.

While dairy may be an entire food group, it is not an essential nutrient.  All the nutrients in dairy are available in other foods.  If you experience these symptoms, you can try removing dairy from your diet.  You may find improved digestion and fewer gut issues or you may find improved nasal congestion, or even less belly fat.

Dairy-free, but love ice cream?  We have your back.  Try our decadent ice-creamy dessert that is super-simple to make.