dr. kari nadeau is an expert in adult and pediatric allergies. she's head of a special allergy research center at stanford university. >> people are very much living with this disabling worry of having an accidental exposure. >> allergic reactions occur when the body's immune system overreacts to certain proteins in food. while any food can trigger a reaction, about 90% are caused by "the top 8" -- milk, eggs, peanuts, tree nuts, fish, shell fish, soy and wheat. when the immune system launches a protective response, cells release antibodies known as i-g-e or immunoglobin e. >> an i.g.e. is the match that lights the fire behind allergy. within 6 minutes you can have this very serious allergic attack. this young lady presented here after ingesting some cashews. >> this is what anaphylaxis looks like. this little girl's mother gave techknow permission to use this video. >> anything on her tummy? yep, and on her back too. >> and she's hot to the touch. >> so gieve, come and take your food now. >> nine year old gieve gregg is allergic to tree nuts and