Food allergies continue to be on the rise among US kids according to a report released Wednesday by National Center for Health Statistics, part of the US Centers for Disease Control and Prevention. More exactly, food allergies rose 18 percent from 1997 to 2007, the report said, meaning that about 3 million children or four out of every 100 suffered from a food or digestive allergy in the previous 12 months.

The report, called “Food Allergy Among U.S. Children: Trends in Prevalence and Hospitalizations” had two sources: the National Health Interview Survey, which sampled some 9,500 children in 2007; and the National Hospital Discharge Survey, which includes 270,000 inpatient records from about 500 hospitals.

“It is a significant trend – food allergies do appear to be continuously increasing over the decade. And if you look at hospital discharges with any diagnosis related to food allergy, there has been a significant increase,” CDC health statistician Amy Branum, MSPH, lead author of the report, said.

More exactly, the number of hospital discharges jumped from about 2,600 a year in the late 1990s to more than 9,500 annually in recent years, the CDC results showed.

According to the study, the foods most likely to cause allergies are milk, eggs, nuts, fish, soy and wheat. Kids having allergies because of these foods usually experienced respiratory problems such as wheezing, as well as a rash, diarrhea or vomiting.

Food allergies usually show up very early – within the first six months – according to a study made by the Food and Drug Administration and published in this month’s Pediatrics. The study surveyed 2,441 mothers and showed that about 6 percent of babies have food allergies by the end of their first year.

The CDC report also found that kids experiencing milk allergies get other allergic symptoms, like asthma much more often than kids without food allergies. More exactly, 29 percent of kids with food allergies, but only 12 percent of kids without food allergies, also have asthma. Twenty-seven percent of kids with food allergies, but only 8 percent of kids without food allergies also have eczema or skin allergy. And last but not least, more than 30 percent of kids with food allergies, but only 9 percent of kids without food allergies, also have respiratory allergies.

Parents who have children with allergies need to take them to the hospital right away.

“I would never ignore a rash. At a minimum, contact a pediatrician,” said Hugh Sampson, MD, director of the Jaffe Food Allergy Institute at Mount Sinai Hospital, New York.

However, although nearly 21 percent of children in the FDA study had some food-related problem, only 8 percent of all children saw a doctor.

Especially for these parents, the Food Allergy and Anaphylaxis Network offers information on foods producing allergies and how to manage them on their Web site, www.foodallergy.org.