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Lactose vs cow's milk protein - do you know the difference?

Before I start I need to make the disclaimer that I am not an expert in this area - I am simply writing this from information I have learned over the last few years, to help clarify a few points. If you believe your baby has one of these issues then you should see a relevant health professional before making too many changes - I am happy to see clients as an initial step and to help you find the right information and resources.

1st Match - Edited to add - I attended a conference in mid-February 2020 specifically on breastfeeding and allergies, and from the information shared there I am more confident that this information is correct. Some new information has been added.

lactose intolerance vs cows milk protein intolerance, whats the difference

First lets start with some definitions:

Intolerance vs allergy

An intolerance is something that the body does not like and causes symptoms such as pain, vomiting, diarrhoea, etc. Technically you can still have it, it just won't be a pleasant experience. An allergy is an immune response to a substance. Symptoms can range from rashes to breathing difficulties. Allergies can be life threatening and it is best to avoid substance.

An example from my own experience is that I am sensitive/intolerant to morphine - it causes vomiting and stomach issues, but I can have it if I really need it (the benefit of having it might outweigh the risk). On the other hand I am allergic to penicillin - the symptoms I had were swelling and a rash. Doctors have advised that I do not have it again as the next time could be life threatening.

What is lactose

Lactose simply means 'milk sugar' - it is the carbohydrate found in all animal milks. Just like fructose is 'fruit sugar', glucose is the substance that the body uses for energy, sucrose is the combination of fructose and glucose....get my point?

Lactose is in human or 'breast' milk - you cannot remove lactose from human milk - the body puts it there. And you cannot change the amount of lactose that is in human milk - even if you eat 0 molecules of carbohydrates, your body will produce lactose and put it into the milk. Lactose is very important for a baby - it is their source of energy and helps cells grow.

It is very rare for a baby to be lactose INTOLERANT as it can be life threatening, especially if they are very young. This is because it is NORMAL for lactose to be in breastmilk. Therefore it is NORMAL that they can tolerate lactose. True lactose intolerance does exist but these babies are often very sick from a few days old - because they cannot process the lactose they need for their cells to do work.

Now, before you start saying 'ah but my husband is lactose intolerant' - yes, older children and adults CAN be lactose intolerant, because they no longer need human milk to survive.

Lactose is milk sugar

What is more common is lactose overload and cow's milk protein intolerance/allergy....

Too much lactose can irritate the lining of the intestine. This can cause symptoms such as mucous in the stool, diarrhoea, irritability, etc. But how do we fix this if we cannot adjust how much lactose is in the breastmilk?

Usually lactose overload happens because the gut is already irritated (such as from an illness like gastroenteritis), or medication, such as antibiotics. Other causes can be oversupply, or not allowing the baby to drain the breasts (such as in timing feeds and switching sides too often). First you need to fix the underlying issue.

Another common issue that is often mislabelled as lactose overload is cow's milk protein intolerance/allergy.

Lactose and cow's milk protein (CMP) are 2 DIFFERENT substances. As I said before lactose is milk sugar. Cow's milk protein is quite simply that - a protein that is found in COW's MILK.

Cow's milk protein intolerance can cause lactose overload

CMP intolerance can cause lactose overload - mucous in the stool, irritability, as well as reflux (to the point of not gaining weight well), eczema-like rashes, and congested breathing.

This is why some people say 'my baby did better on lactose free milk' - because there is less lactose to irritate the gut. But the intolerance to cow's milk protein (which is still found in lactose free milks) is still there and you may still notice some symptoms.

CMP allergy is more serious - since it is an allergy, it can be life threatening.

It was noted at the conference in February that symptoms may actually worsen with formula after a couple of weeks or more - the benefit of breastfeeding has 'worn off' and so they do not have the added protection breastfeeding gives. Often more complex formulas are then needed, which can be expensive and difficult to find.

Can you continue to breastfeed a baby with a CMPI or CMPA?

The simple answer is yes, but you need to remove ANYTHING that might contain cow's milk protein from your diet. And this doesn't just mean 'diary' products - it means anything that contains cows milk (I have heard of sausages having cow's milk in them!).

But before you go self diagnosing CMPI/A and doing elimination diets please see a qualified professional. And another point noted at the conference is that elimination diets should only be done for 4-6 weeks and then cow's milk added back in slowly to see what the baby may react to.

Often soy is mentioned as causing the same issues as CMP and so some recommend eliminating soy at the same time. At the conference it was recommended not to do this as then you do not know what has caused the improvement. My point of view is that you could eliminate both and then add them back in one at a time.

As I said above I am happy to see clients initially if you believe this might be an issue for you and then refer you on as necessary. I can be contacted on 0405 427 998 or go to for more information


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