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.