Experts say they can't explain why the number of children with food allergies has increased 18% in the past decade.
About 4% of people under 18 -- or 3 million children -- had food allergies in 2007, according to a report released Wednesday from the National Center for Health Statistics, part of the Centers for Disease Control and Prevention. About 9,500 a year were hospitalized for food allergies from 2004 to 2006 -- more than 3 1/2 times as many as in 1998 to 2000, the CDC study shows.
The foods most likely to cause allergies are milk, eggs, nuts, fish, soy and wheat, the study says. Allergic reactions can include respiratory problems, such as wheezing, as well as a rash, diarrhea or vomiting.
Because so many studies have documented an increase in allergic diseases, doctors believe the increase is "real," rather than the result of greater awareness or expanded testing, says A. Wesley Burks, a co-author of the American Academy of Pediatrics' 2008 food allergy recommendations who was not involved in the new CDC report.
The academy encourages mothers to breast-feed for four months to reduce the risk of some allergies. But after infants are 6 months old, there's no evidence that avoiding certain foods protects them from allergies, the academy says. There's also no evidence that pregnant or nursing mothers should avoid certain foods.
Food allergies may be the first sign of lifelong problems with allergies, research shows.
The CDC report says children with food allergies are two to four times as likely to have related conditions, such as asthma or other allergies, compared with kids without food allergies.
Food allergies typically show up very early -- within the first six months -- according to a Food and Drug Administration study in this month's Pediatrics, which surveyed 2,441 mothers. About 6% of babies have food allergies by the end of their first year.
Babies often "grow out of" food allergies, says Scott Sicherer of New York's Mount Sinai School of Medicine.
These same children, however, often develop hay fever and asthma, says Sicherer, who was not involved with the new studies.
Authors of the FDA study note that it's important for parents to bring children with suspected food allergies to the doctor. Although nearly 21% of children in the FDA study had some food-related problem, only 8% of all children saw a doctor.
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