Nov. 11 -- MONDAY, Nov. 10 (HealthDay News) -- The number of U.S. children allergic to foods such as peanuts, milk and fish is rising rapidly.
At the same time, researchers are working on new approaches to treating these allergies, according to two reports to be presented Monday at the American College of Allergy, Asthma and Immunology's annual meeting, in Seattle.
An estimated 3 million children under 18 had a food allergy in 2007, an 18 percent increase since 1997, according to the U.S. Centers for Disease Control and Prevention.
"The problem is even more than numbers," said Dr. Sami L. Bahna, a professor of pediatrics and medicine and chief of allergy and immunology at Louisiana State University Health Sciences Center. "The severity of food allergies is going up."
There has been an increase in severe rashes; severe attacks of airway obstruction, called anaphylaxis; and intestinal problems, Bahna said.
What's more, the method of exposure that results in an allergic reaction is also changing, Bahna said. "People used to react by eating the food, but there are many people now that react by touching or smelling the food," he said.
Food allergies aren't the only allergies on the rise, Bahna said. "All the allergies are increasing -- asthma, hay fever, eczema," he said.
Several factors are contributing to the increase in allergies, the expert said. The first is the so-called "hygiene hypothesis," which holds that people in industrialized countries are living in increasingly sterile environments. As a result, their immune systems don't have to fight as many infections, so those systems can become hyperactive.
"When there is some degree of unhygienic conditions, the immune system from infancy adapts and develops to fight infection," Bahna said. "Cleanliness, antibiotics, whether they are needed or not, and vaccinations are allowing the immune system to develop as if 'I don't need you,' " he said.
Other reasons include the increased use of antacids among children, which prevents stomach acid from doing its job, and the increased use of multivitamins, which is associated with an increase in allergies, Bahna said.