Every three minutes, a food allergy reaction sends someone to the emergency room in the US. It's an alarming statistic that worries parents and adults across the nation. In some extreme cases, mere nanograms of peanut protein can trigger a dangerous reaction and a mad dash to the hospital. The US Centre for Disease Control reported that from 1997 to 2011 the number of children with food allergies increased 50 percent. Over 15 million Americans suffer from food allergies, at a cost of $25bn each year. "A hundred years ago people did have food allergies, but it wasn't to the same epidemic proportions that we are suffering from now," says Dr Kari Nadeau, an expert in adult and paediatric allergies and head of a special allergy research centre 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 and food. While any food can trigger an allergic reaction, about 90 percent are caused by eight sources: milk, eggs, peanuts, tree nuts, fish, shellfish, soy and wheat. When the immune system launches a protective response, cells release antibodies known as immunoglobulin E (IgE). "An IgE is the match that lights the fire behind the allergy, within six minutes you can have this very serious allergic attack," Nadeau explains. The marching order for decades has been avoidance and training children to become allergen inspectors before consuming certain foods. But, it's very difficult to track and vet every plated meal or crumb that a child with a food allergy might come across. Accidental ingestion happens and, for some, it can be fatal. So now, instead of avoidance, experts are looking at new ways to retrain the immune system and develop new treatments to desensitise food allergies. - Subscribe to our channel: http://aje.io/AJSubscribe - Follow us on Twitter: https://twitter.com/AJEnglish - Find us on Facebook: https://www.facebook.com/aljazeera - Check our website: http://www.aljazeera.com/