Milk allergy is the most common form of food allergy found in humans, but you don't have one and neither does your baby

Well, maybe, but probably not. Even though milk allergies in infants and very young toddlers are the most common food allergy, they still occur in only about 2.5 percent of the population in the US and other Western groups. For this reason, I was rather perplexed some months back when I encountered a group of eight mothers randomly assembled, three of whom had infants with milk allergies. Two of the mothers had started to eliminate all dairy from their diets, including eggs, in order to reduce the effects of the milk allergy on their infants. Who were breastfeeding.

I realized that something was terribly wrong with this picture, beyond the simple fact that eggs are not dairy, and I also realized that there was not much I could do about it. The mothers had spent considerable time and effort on reducing diary in their own diets and I think they felt they were making progress. Their breastfeeding infants were starting to show fewer symptom's of milk allergy. I wonder if they thought the final act in reducing dairy ... swearing off chicken eggs ... was the coup de grace for this nasty allergy to cow's milk.

Studies have shown that between five and fifteen percent of Western babies are thought by their families to have milk allergies. In the situation I had observed, the percentage was much much higher. I suspect (but do not know) that the lower percentages found in the studies is from eliminating breastfed-only infants from a questionnaire on allergy to cow's milk. Because they (the babies) aren't drinking the cow's milk. So they can't be allergic to it! What I was observing was mothers thinking that they could pass the allergenic substance on to their offspring by consuming the milk of the beast then secreting it from their breasts. That, I'm pretty sure, is highly unlikely. There are two proteins in cow's milk (and the milk of other bovids) that account for all or almost all milk allergies, and I'm fairly certain that, like other proteins, these are disassembled by the human digestive process and mainly turned into amino acids or other bits and pieces that may later be used to build new, human style proteins. If anyone is aware of any research that demonstrates that I've got this wrong, please pass it on to me.1 (See this and links for in .... it may be that cow's milk protein affects infants via the mother in a small percentage of colic cases, ca 10%.)

Why do so many more people think their children have milk allergies than actually do? I think there are a few reasons. One factor must be that the list of symptoms of milk allergy is long and very similar to the list of pukey-poopy-blotchy-icky things that infants normally do anyway. Check out the symptoms as listed on the Mayo Clinic web site: Hives, Wheezing, Vomiting, Loose Stools, Diarrhea, Abdominal cramps, Coughing, Runny nose, Watery eyes, Itchy skin (often around the mouth), Colic. This list reads like a list of qualifications for being a baby.

Another reason is that food allergies are scary these days. We hear about people who drop dead if they walk near a peanut, and thus we get scared of food allergies, so naturally when the baby develops a rash on its lip, we gravitate towards that explanation. Fear drives culture more than it probably should, I'm afraid.

Yet another reason is the prevalence of so-called "lactose intolerance." Lactose intolerance is NOT a milk allergy. It is vastly, hugely, utterly different. Milk allergy is an inappropriate immune response to one or the other of the aforementioned PROTEINS in milk. So called lactose intolerance is the lack of sufficient lactase, an enzyme, to allow digestion of lactose, a SUGAR, found in milk. And I call it "so called" because it is not a disease or condition as indicated by the word "intolerance." Rather, it is the case that mammal adults don't drink milk. Therefore, the enzyme used in obtaining energy from the milk's sugar is typically not manufactured, because the gene that codes for it is not expressed, in adult mammals.2 Except some odd populations of humans. The vast majority of humans do not digest lactose as adults, only as babies, like normal mammals do. One of the odd and rare populations that does so is Western Europeans, and Western Europeans have another somewhat unique trait: They define everything else in the universe in relation to themselves. So, if Africans and Asians and Native Americans and Australians and even a bunch off other Europeans are normal mammals and don't digest milk as adults, then that condition ... being normal ... must be the disease, because Sir Quimby Whitherspoon (randomly chosen western white male name) DOES digest milk as an adult. Which, when you think about it, is kind of perverted.

In any event, conflating lactose intolerance (so called) and milk allergy may cause one to think that milk allergies are very common because, after all, all your Asian and Jewish friends have it.

Finally, there is the coddling of people like me and institutions like the Mayo Clinic. I really should have interjected into that conversation a few months back a strong doses of skepticism and science, and caused learning to happen but I could see that I would have been clashing with world views and having little effect, and besides, I was focusing more on the question of vaccines and less on diet. And, the Mayo clinic does not help when they state on their web site, in the section on milk allergies, that this is the most common form of food allergies in humans (correct) without noting that it is actually more rare than most people think and is often self-diagnosed (by parents of infants) incorrectly. I have no idea why they don't say that.

So, to summarize, human babies rarely have milk allergies. One in fifty babies, roughly, might have one. People over diagnose this condition so you probably know far more babies said to have a milk allergy than actually have one. In order for a baby to demonstrate an allergy to cows milk it must drink cows milk. Milk allergy is not lactose intolerance, and is an utterly different thing, with a different biology and mostly different symptoms. And finally (not mentioned above) a human baby's allergy to cow's milk is likely to go away by itself, probably while the baby is a toddler.

Think about it. Food allergies must be pretty rare, and when they occur they must mostly occur with foods that our species did not evolve eating a lot of. Since babies drink mother's milk and all milk is made of animal proteins, this sort of allergy stands out as being a bit unexpected, but it is, after all, an allergy to proteins that would not normally have been consumed by our forager fore-bearers. Note that "meat allergy" is so rare that you've never even heard of it. Allergies to plants, evolutionary biology would predict, would be most common for historical mismatches between population and plant. Processed grasses are now widely eaten by humans, but in the past were not eaten by very many populations (wheat, corn, etc.). Root allergies must be very uncommon. I would predict that there would be more allergies to new world plants than old world plants but the diversity of plants and disparity of diets is too large to make much sense of that relationship. (Although we don't eat it, it is interesting that New World mammals seem unaffected by poison ivy ... it is a major browse for deer ... but humans, from the old world, are affected.)

And yes, I think the mommy instinct is a world view. Or at least, a very powerful point of view that is hard to engage from the outside. I wonder, do they talk about this in middle school and high school health and "home economics" classes? I'm guessing not.


Horst, A. (2002). Frequency of cow's milk allergy in childhood Ann Allergy Asthma Immunol, 89 (6 supplement 1), 33-37

1According to a recent review, "...only about 0.5% of exclusively breast-fed infants show reproducible clinical reactions to CMP and most of these are mild to moderate. This might be related to the fact that the level of CMP present in breast milk is 100 000 times lower than that in cow's milk...."

2Well, actually, we don't know that the gene is turned off in all adult mammals. What we do know is that it is not "used" in adult mammals. Therefore, it is not under selection to be maintained as an adult trait, and thus, most likely, it is turned off because there is a cost to making an enzyme (and to expressing a gene, for that matter). Thus, we might see the gene mostly turned off or turned off or on randomly in various mammal populations.


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Your Old world New World poison ivy comment really piqued my interest. Would this tolerance also apply to people from Ol vs New World. I know some people are very sensitve to poison ivy, but neither I nor my mother have ever had any rxns to it. (But I also don't press my luck). Considering my Native American heritage, could this account for the lack of allergic response or are we some lucky ladies?

Toxicodendron species are common in much of Asia as well, and all contain the same urushiol as poison ivy. Plus, Old World species like cats and dogs aren't affected, either, are they?

. Would this tolerance also apply to people from Ol vs New World.

Not so far as I know. There is a lot of variation. As an archaeologist working in this area, I can tell you some amazing stories. But Native Americans are susceptible to PI. But less susceptible? I don't think there's sufficient data on that.

Chelydra: Same or similar? These are very complex molecules, and PI has more than one irritant, and the delivery may matter. "Plus, Old World species like cats and dogs aren't affected, either, are they?" How would you know, they're covered with fur! Actually, I have no idea.

But yes, the whole PI thing is purely speculative.

Warning: There may be people on the internets who will show up screaming that you are not allowed to speculate. Warning.

I am told when I was a small child I was allergic to cows milk and could only drink goat's milk. I always thought it was odd how I could be allergic to one kind of milk and not another. [/random]

G: Maybe. But there is a lot of goat-woo out there, so I would not make any assumptions. Kids who are alergic to cows milk may or may not be alergeic to the milk of other bovids. Depends.

I can say with absolute certainty that allergies to milk can vary depending on the kind of milk.

I am allergic to milk, (yes, I was actually tested), however I have the other reaction, (hyperactivity). One thing we did try when I was a kid was goat's milk. While cow's milk simply made me annoying, goat's milk had me climbing the walls[1].

I also know of other cases where someone made the switch and the reaction went away.

[1] Not a figure of speech. I was halfway up when my mom caught me.

By Rick Pikul (not verified) on 20 Jan 2011 #permalink

I happen to know a guy who is half Native American (roughly, although I reckon it's hard to say) along with half (again, roughly)Western European ancestry. Poison oak nearly killed him on two separate occasions that I'm aware of...

By ScienceAndHonor (not verified) on 20 Jan 2011 #permalink

While my mother is woo-prone in a lot of ways, I'd be surprised if there was a lot of "goat woo" (which is a delightful phrase I need to find a way to work into daily conversations) when I was a kid. I am pretty confident that I was allergic to cow's milk from the stories I've heard from other relatives, I just always assumed -- because I didn't really think it was possible to have an issue with one and not the other -- that I was allergic to goat's milk too and my mother just refused to believe it. But who knows now, since I outgrew my [cow] milk allergy as a child and no longer have an issue with any dairy.

I think it depends. In fact, it may even depend on the individual goat or cow for some people. It is an allergy, which means the shape of a particular protein is acting like an antigen. Certain protein parts don't vary across individuals, and can even be the same across species (more likely related species but not necessarily) and others can vary a lot more, and vary across individuals.

I understand your main points - and agree with many. However, one point is somewhat misleading. While "meat allergy" may not be something people have heard of, there are allergies to specific animals/meats - for example, I was allergic to chicken when I was younger, and am still allergic to fish.

Matt, you are correct. Again, though, the farther away in phylogenetic relationship the more likely an allergy. I know of no one who is allergic to monkey, for instance, but molluscs are a whole other story.

"[1] Not a figure of speech. I was halfway up when my mom caught me."
thereby prematurely ending a promising acrobatics career.

"Does not make it not perverted. "
men should not be drinking cow's or goat's milk {/wink}

btw hasn't been mentioned here, goats love munching ("browsing") poison oak/ivy. but does "anyone" suspect the irritants can be transferred? (like allium flavor supposedly can 'carry thru' into milk.)

and then there's the old tale (about nat-ams) eating early poison ivy shoots to confer skin immunity...

Interesting Greg. I grew up drinking cow's milk but somewhere around age 35 or so started to have a lot of trouble drinking it and by age 50 anything more than a couple of ounces would give me severe cramps and a good case of the Mexican two step - however goat's milk does not have that effect on me. I wish I could go back to cow's milk as it is 1/2 the price of goat's milk.

You may be lactose intolerant. That may not explain why the Goat Milk is OK, but with the goat-woo factor there may be magical properties of some kind that have an effect.

Jews are lactose-intolerant?

Then why does the Torah praise the land of Canaan as "flowing with milk and honey"?

By Riman Butterbur (not verified) on 23 Jan 2011 #permalink

Riman, interesting point. You've found an inaccuracy in the Bible! We've got to tell someone!

But seriously, the Maasai, who get a very large percentage of their calories from their cow's milk, are also lactose intolerant and they have an expression very much like "land of milk and honey" ... probably for this reason:

Or, more likely, there are a lot of people, lots of different groups, who call themselves or have called themselves Jews. Only some of them are lactose intolerant today ... Ashkenazim, those from around Germany originally.

My daughter was diagnosed as lactose intolerant at the age of 3 months. Since I was breast feeding her, I had to remove dairy from my diet until she was weaned. If I ate dairy foods, she'd projectile vomit and have screaming Mimi fits of diarrhea that I thought would never end. Removing dairy from my diet worked like a charm for HER, though I became bitter and fantasized about fabulously creamy foods I wasn't able to eat.

Her Pediatrician did suggest I try eating goats cheese, as it's easier to digest, but besides being mostly unpalatable my daughter couldn't tolerate that either. I think a lot of people confuse intolerance and allergy; you may grow out of an intolerance but an allergy is likely to be around for life.

Linda, Lactose intolerance is the absence of lactase, an enzyme that is part of the process of digesting lactose, a sugar which is digested in the small intestines, or not. If not, it passes along the small intestines and to the large intestines. Sugars are not really supposed to be in the large intestines, but the bacteria there seem to do interesting things with it, thus causing the problems one has associated with lactose intolerance.

You could not possibly have pasased lactose from your diet to your daughter vis your breast milk. You were producing lactose, of course, as part of your breast milk.

It is very rare that a 3 month old would be unable to produce lactase. If that were the case, she would have been unable to digest the sugar in your breast milk. She would have required a special diet and would not have been able to breast feed, or at least, not much. (Not digesting lactose is not fatal, of course.)

I'm pretty sure there was something else going on with you and your daughter, and your pediatrician was confused.

Buddy you are clearly an idiot, with what seems to be very little knowledge of what you are talking about. Cow's milk protein CAN be passed through mother's breast milk, so get your research right.

"Laura" it may well be true, but until you produce a citation or two from peer reviewed research or an otherwise credible source you are on notice. Let's have the goods!

Also, let me know when you find it any evidence supporting cattle proteins being passed through mother's milk from chicken eggs.

Cow's milk protein can be passed through breast milk. I saw this first hand with my son. He would not have bowel movements for two to three weeks while nursing. Eventually he had an anaphylactic reaction to milk when he ate a piece of cheese. When I avoided milk in my diet he began to have regular bowel movements. He is six years old and still severely allergic to milk. This article does not do much to support those who are really suffering from severe milk allergies.

Meredith, your experience does not demonstrate the point you are asserting. Also, how do you know your son is allergic to cow's milk? Has he been checked for this?

He may well be,of course.

I'm trying to be supportive, but only with reference to reality.

Margaret, thanks for that reference, it is interesting and I don't think I had seen it when I first wrote this post (it wasn't published yet). It does pretty much support what the OP says.

No citations yet forthcoming.

In an allergic reaction to CMP the digestive system is not activated. The immune system is! This means that cows milk proteins can be in mother's milk in an undigested form, leading to allergic reactions in breastfed infants. For adults the allergy goes underground and could manifest as disease. In our clinic where we work with people suffering from a variety of diseases we find that more than 50% of those have a hidden allergy to dairy products, and those not allergic to dairy have an intolerance to lactose. It is estimated that 75% of adults worldwide show some decrease in lactase activity during adulthood. The frequency of decreased lactase activity ranges from 5% in northern Europe through 71% for Sicily to more than 90% in some African and Asian countries.

By Hans de Rycke (not verified) on 30 Aug 2013 #permalink

Having avoided cows milk while breast feeding (it seemed to reduce colic symptoms) I called my doctor for advice when weaning. He took your attitude (over protective mother etc etc) and recommended that I try her with a teaspoon of (cows) milk based formula to see how she goes. It dribbled down her chin and within 3 minutes, every spot of skin that the milk had touched was a bright red blistering hive. The GP quickly prescribed soya based formula milk. 3 years later she was accidentally given a teaspoon of dairy ice-cream by a member of nursery staff who took your view of over protective mother etc and promptly went into an anaphylactic reaction. I hope she will grow out of it but until then I am fighting a constant battle with people who think I'm being over protective, making it up or confusing it with an intolerance. By the way - she also has difficulty (although less severe) in digesting egg proteins. I know they are not dairy, but she has to avoid them too.

You are not being over protective.

I have the test that says I'm allergic to milk. I do have intense intestinal discomfort from dairy, and nasal / bronchial symptoms. My question is I don't get diarrhea from it, but I do suffer from severe constipation, could the dairy be to blame? I can't find any information stating that a dairy allergy causes constipation any ideas?

Cows milk protein intolerance is diagnosed by a fecal occult blood test, if the test is positive for blood then cows milk protein intolerance is diagnosed and the mother must eliminate all cows milk and cows milk ingredients from her diet and the symptoms subside. In severe cases a biopsy of the stomach is done.