This month’s issue of the Journal of Allergy and Clinical Immunology has a symposium on food allergy.
Until recently it has been recommended that a good strategy to reduce risk of children developing food allergy was to promote exclusive nursing as a food source, to have the mother avoid highly allergenic foods and to delay weaning with introduction of solid foods.
However, despite the implementation of this approach in a number of countries in Asia, Europe and North and South America, there has been no reduction in the incidence of food allergy. The recommendations were made based on individual facts that are true, but that unfortunately do not lead to the desired outcome.
It is definitely true that mother’s milk is the best and most complete of infant nutrition. It is also true that mother’s milk contains a host of proteins and immune globulins that provide protective immunity to the infant. It is also true that early exposure to foods other than mother’s milk can lead to the development of food allergy.
From all these facts it was assumed the feeding recommendations also would be the best course to follow.
Once the potential benefit of this dietary approach was actually studied however, it was quickly learned that it did not provide the desired results. As it turns out a crucial fact that was previously unknown makes a pivotal difference.
If infants have early exposure to non-breast milk foods through skin contact, this is what leads to allergic sensitization. This has been born out in animal model research. Paradoxically, the food allergy development through skin contact can actually be prevented by early oral exposure to the food, e.g., from parents’ hands, kisses, etc. A good example of this phenomenon has actually been recognized for quite some time and it has to do with nickel allergy.
If a child’s first exposure to nickel is from pierced ears (skin exposure), there is up to a 40 percent chance of the child developing nickel allergy. If, on the other hand the child has oral nickel exposure from placement of orthodontic braces prior to ear piercing, the risk of nickel allergy is almost zero.
At this point in time the American Academy of Allergy has no specific recommendation. There are, however, numerous randomized controlled studies that are being conducted comparing the early exposure to foods such as peanut, milk, wheat and egg versus strict avoidance of these foods. Such studies will lead to a new evidence-based recommendation on how to prevent food allergy.