A scientific study due to be published in the American medical journal Pediatics (December 2009) has found a massive 18% increase in reported food allergies amongst US children (under 18 yrs of age).  This increased reporting of food allergies took place over the last decade between 1997 and 2007.  While between 1993 and 2006 ambulatory visits to the doctor for food allergies have tripled.  In 2007 alone, 3.9% of US children reported food allergic conditions.  The most severely affected were ethnic minorities such as Hispanics. In 2005 to 2006, an estimated 9% of US children had detectable peanut IgE in their blood on allergy testing while over the same period hospitalisations with a diagnosis of food allergy also tripled. It is uncertain whether this trend is due to a true increase in food allergic diseases or represents increasing allergy testing and physician and parental food allergy awareness.

http://pediatrics.aappublications.org/cgi/content/abstract/peds.2009-1210v1