About 8 percent of children, or nearly 6 million in the U.S., have a food allergy, a much higher rate than previously estimated, a new study suggests. Not only is this estimate higher than some previous research has reported, allergic reactions are often severe and that many kids have more than one allergy, according to the study published online in Pediatrics on Monday. Of the children with confirmed (or probable) food allergies, about 39 percent had had severe reactions in the past, and 30 percent had more than one allergy, the study found. In the current study, researchers at the Northwestern University Feinberg School of Medicine surveyed parents of more than 38,000 children about whether their child had been diagnosed with a food allergy and had one or more of a number of symptoms, including anaphylaxis; swelling of the lips, eyes or face and skin rashes or hives. The study pinned down peanuts (25 percent of food-allergic children), milk (21 percent) and shellfish (17 percent) as the top three allergens. Severe reactions were most common among children with tree nut (more than 50 percent) and fin fish (more than 40 percent) allergies. The reactions were more likely among 14- to 17-year- olds compared with 0- to 2-year-olds, and more likely in children with multiple food allergies, the study found. \"These findings provide critical epidemiologic information to guide strategies for the prevention of food-induced reactions and for the diagnosis and management of childhood food allergies,\" the study noted.