BALTIMORE, Maryland -- One in 13 children has a food allergy. That's about two in every classroom.
The approach to food allergies is changing and could involve introducing foods that parents used to avoid giving to their children early in life.
Still, a rise in food allergies has given new parents a cause for concern. Common allergies are milk, eggs and nuts.
Reactions can be serious and even life-threatening. And the allergies are on the rise.
"What's fascinating is that in the last 20 years, allergies of all kinds, including food allergies have actually doubled roughly," said Dr. Gaurav Kumar, LifeBridge Health in Baltimore.
No one is sure why.
One explanation is that we've made are environment too clean with too few germs. It's called the hygiene theory.
"Our immune system has had less to do and therefore it's actually started reacting to other things," Kumar explained.
In 2000, the American Academy of Pediatrics made a recommendation saying parents should avoid giving their children certain foods until later in a child's life.
That included avoiding milk until age 1, avoiding eggs until age 2 and avoiding nuts until age 3.
But in 2008 the academy struck down those guidelines, saying it was unclear what the right age should be.
"More recently there is actually really intriguing evidence that suggests that for certain kinds of things like peanuts and eggs, it may be beneficial to introduce them earlier in a child's life -- sometimes as early as 4 to 6 months of age," Kumar said.
His message is to introduce these foods in a safe manner closely monitored at home. If a baby has a history of food allergies, introducing the foods should be done under the supervision of a pediatrician.
Parents should talk to their baby's pediatrician about the best strategies for introducing new foods.