Egg Allergies and Early Introduction Got You Scrambled?
Egg allergies are the third most common food allergy although a large percentage (~80%) of children will outgrow them by age 5. And of those children with egg allergies, some are only allergic to uncooked or lightly cooked eggs such as in mayonnaise or french toast. They can safely eat eggs in baked goods like muffins. We know early introduction of peanuts is incredibly beneficial to reducing the risk of an allergy, but what about eggs?
First let’s take a look at what makes eggs an allergen, or, as you may want to ask:
“Why can some people eat baked eggs but not scrambled or uncooked eggs?”
The biggest allergenic egg proteins are found in egg whites. Although ovalbumin (OVA) is the most abundant protein in egg white, ovomucoid (OVM) has been shown to be the more dominant allergen in egg allergies. The egg yolk has wholly different proteins, which do not seem to cause allergies very often (but nothing is 100% so more on this below).
OVA, the most common protein in egg white, denatures (breaks-apart) at high heat. OVM, on the other hand, remains stable even at high heat. Some people are only allergic to OVA. When the egg is baked, the OVA can no longer bind with the IgE factors that cause an immune response. Therefore, people with the OVA allergy can eat well-cooked egg.
For those with an allergy to OVM, it does not denature when the egg is heated. So people with an OVM allergy cannot eat any egg. That's why, when testing for an egg allergy, you actually have to test for two unique allergies.
A surprising finding is that for people who are allergic to uncooked eggs, but not cooked eggs, regularly eating cooked eggs can increase the chance of outgrowing the OVM allergy!
If yolks don’t have OVA or OVM, why can’t people with an egg allergy eat yolks like in custard?
It is very difficult to entirely separate egg white from the yolk. So exposure to egg white protein still occurs when the two are separated, but the level of exposure would vary from meal to meal. Egg yolk also contains proteins which can cause a hypersensitivity reaction (so it is also technically possible to be allergic to egg yolk and not egg white).
Has early introduction of egg allergy been studied?
Overall the results are that early egg introduction is beneficial, even though no results have been as strong as the results of the LEAP study. A broad meta-analysis created a ‘weighted-average’ result of all the egg studies based on the number of patients they enrolled and the rigor of their the methods. In sum, it found that early egg introduction reduced the rates of allergies and sensitization without increased risk for babies. (For detail, see below)
One surprising finding from both the STAR study and the HEAP study is that a number of babies were already sensitized to whole egg powder or egg white powder even when they started the study at 4 months old. In the EAT study, where they used well-cooked egg, no reaction was seen. This is consistent with the evidence that consumption of lower allergenicity forms of allergenic foods facilitates outgrowing allergy to those foods. The EAT study report suggested “raw egg is the most allergenic form of egg and clearly, introducing it to young infants, whether as pasteurized egg white powder (HEAP) or pasteurized whole egg powder (STAR) is not to be recommended.”
So should I Introduce eggs to my baby early as well?
Again, as with peanut, it seems like the biggest benefits go to those children who are high-risk (children with eczema, parents with food allergies, siblings with food allergies). For everyone who doesn't have clear signs of risk, introducing foods freely, and as early as safely possible, is the best strategy. In general, it makes sense to start with baked eggs, then scrambled eggs, and lastly uncooked (i.e. mayo) eggs.
However, our experience has been (and the data proves) that the amount of time it takes to cook or bake eggs, then puree or mash them means most parents won’t introduce eggs nearly as early as they should. They seem to wait until their baby is almost a year old. So at Lil Mixins we are developing an egg powder which will be scoop-able and blend into baby food. As always, we are committed to using the highest quality ingredients, without additives. That’s not easy, and it's going to take time, but we want nothing less than the best.
Results from the Meta Analysis
Summaries of the Egg Allergy Prevention Studies Mentioned Above