Food Allergy May Not Always Be Caused By Ingestion Of Food

January 12, 2010

The exact reason an infant develops an allergy to a particular food is not known.  There is no doubt that genetics has a lot to do with it, and infants who have parents or siblings with allergies are at increased risk.  There are many theories as to what may contribute to the development of a food allergy in an infant.   When you think about how many different kinds of foods and potential food allergens an infant is exposed to, it becomes obvious that the development of an allergy to a food is somewhat of a rare occurrence.  The usual course of events is that the consumption of a food leads to a tolerance of the food by the body.  Nature favors this as food is so important for continuation of life.  When an allergy to a food develops, the immune system of the body is reacting against the food with an allergic reaction.

One theory is that food allergy may occur if the body is exposed to the food through the skin, before exposure through the gastrointestinal tract.  The immune system of the skin processes the food allergen differently than the gastrointestinal tract and this results in the development of allergy.   Skin exposure to food proteins in the environment can occur through contact with tabletops that have food proteins on them, the hands of a family member, aerosolized dust of food proteins or from exposure to moisturizers that contain food products.  Most moisturizers for infants do not contain food products, however moisturizers used by adults can contain various food products such as almond, apricot or sesame.  If the mother of an infant uses a moisturizer that has a vegetable, fruit or nut as an ingredient, when the infant comes in contact with its mother’s skin, an allergic sensitization can occur.

Think about the following fact.  The United States and England are two countries where peanuts are generally consumed in large quantities, but where, until recently,  it had been common practice to delay the introduction of peanuts into the diet of infants, with a family history of allergy, for the first 2-3 years of life.  In Israel, it is common practice for infants to be given peanuts at a younger age as peanut snacks that are safe for infants are available.  The rate of peanut allergy in Jewish toddlers in England is about ten times the rate of peanut allergy in Jewish toddlers in Israel.  The above theory would explain this by pointing out that the infants and young children in England are likely exposed to peanut proteins in their environment and through their skin before exposure through the gastrointestinal tract and therefore are getting sensitized in an allergic way.  This is just a theory, but it is curious that two genetically similar groups have such very different rates of peanut allergy, with the group that is having peanut consumption delayed to an older age having much higher rates of allergy.

Another interesting fact is that children with eczema have increased rates of food allergy.  However, we don’t know what came first.  Does the food allergy develop because of breaks in the skin that make it more likely for these infants to have exposure to food products through their skin and thus more readily develop allergy?  Or, do these children have a higher rate of food allergy resulting in the development of the eczema?  In other words, what came first, the chicken or the egg?


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: