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Dairy Intolerance: Is it Lactose? Casein? or Whey?

Dairy Intolerance: Is it Lactose? Casein? or Whey?

Having a food intolerance is not fun. It can cause abdominal pain, discomfort, and nausea. It also causes embarrassing symptoms like flatulence and diarrhea. 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 diarrhea.

Lactose is in dairy but is in lower amounts in fermented dairy (e.g. 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. And if you’re taking any medications or supplements, check to see if it’s 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. In Canada, it is considered a “priority allergen” and must be declared on food labels.

So, what are the allergens in milk? You’ve 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 and be considered a true allergy by promoting an IgE response from the immune system. And 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.

However, even if an IgE immediate immune response is not observed, a lot of people still get reactions from the casein and whey and therefore find themselves intolerance to these proteins.

Like lactose, these allergenic milk proteins can be found in other products too. They’re not just in dairy but are often the base of many protein powders as well (ie. “whey” protein powder).

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. And 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 for their protein molecular structure is very similar.

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

Worried about your Calcium Intake? 

While dairy may be often considered an entire food group, it is not an essential nutrient. Calcium is by far the one mineral that most people worry about consuming enough when they decide to remove dairy from their diets. And there is definitely a big misconception that dairy is the only good source of calcium.

Good news! All the nutrients in dairy are available in other foods. 🤓 I put together this quick summary organized by amount of calcium available by serving size. I focused on the foods over 50mg per serving, although my no means is this an exhaustive list. I just wanted to give you a good idea on where you can get non-dairy sources of calcium.

You’ll see I kept yogurt and milk on the list. I wanted you to compare their calcium values to others to give you a good comparison.

Note that the RDA (recommended dietary allowance) for calcium is as follows:

Birth to 6 months: 200mg
7 – 12 months: 260mg
1 – 3 years: 700mg
4 – 8 years: 1000mg
9 – 18 years: 1300mg
19 – 50 years: 1000mg
During pregnancy: 1200mg
Women over 50 yrs: 1200mg
Men over 70 yrs: 1200mg


If you get gassy, bloated, or diarrhea 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.

If you experience these symptoms, I would suggest you try removing dairy from your diet for at least 2 weeks to see if your symptoms improve. You may find improved digestion and fewer gut issues. Or you may find improved nasal congestion, or even less belly fat.

After the 2 weeks, start by re-introducing a higher fat dairy source like cheese to see how you feel. If you have no issues, wait 3 days and then reintroduce yogurt and see how you feel. And then lastly dairy milk should you choose.

Because milk has less fat content that the other sources of dairy like cheese and yogurt, it’s often harder to digest since it’s farther from being “whole”. Sticking with dairy full in fat is easiest to digest.

*Interesting fact, parents who struggle with their children and bedwetting find that by removing dairy or other food sensitivities notice an immediate improvement!

If you’re not sure if you’re reacting to the lactose, whey, or casein and you want some help you identify how your body is reacting, I can help you identify how your body is reacting to each of these components.

Sign up for my free 30 min consultation and get your Whole Body Health Profile to see what underlying problem could be affecting you.

Much Love,













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