Why are allergies on the rise?
It seems like there is an allergy epidemic – and the data backs it up. Food allergies in children has risen 18% from 1997 to 2007. According to the U.S. Centers for Disease Control and Prevention as many as 3 million children under 18 had a food or digestive allergy in 2007. Trying to figure out why is proving to be a difficult question.
A study in the Journal of Allergy and Clinical Immunology revealed that visits to the emergency room at one hospital for allergic reactions more than doubled from 2001 to 2006. The findings reflect a rise in food allergies everywhere, said Dr. Susan Rudders, lead author and pediatric allergist-immunologist. For all adults and children in the U.S., there are 30,000 ER visits because of food allergies annually. Since that estimate is based on a 10 year old report, this figure is likely higher now, Rudders said.
Western diet theory
One theory is that the Western diet has made people more susceptible. A recent study compared the gut bacteria from 15 children in Florence, Italy, with gut bacteria in 14 children in a rural African village in Burkina Faso. They varied substantially. The children in the African village live in a close knit community which produces its own food and they eat a vegetarian diet. By contrast, the European children eat more sugar, animal fat and calorie-dense foods. These factors may result in less biodiversity in the organisms found inside the gut of European children. Sanitation measures and vaccines in the West may control infectious disease, but they decreased exposure to a variety of bacteria. "In a place where you can die [from] infectious diseases, but you don't get allergy, obesity, asthma, inflammatory bowel disease, autoimmune disease, the flora is different," Dr. Paolo Lionetti said.
Other findings support the notion of the "hygiene hypothesis" -- the idea that cases of allergies are increasing because children grow up in environments that are too clean.
"That our immune system is skewed away from fighting infections, and toward fight things that it's not supposed to be fighting, like things in the environment or foods -- that's one thing that people think may be in play," Rudders explained.