The prevalence of food allergy in children and adolescents younger than 18 was 8% (95% CI 7.6 to 8.3), according to Ruchi S. Gupta, MD, of Northwestern University in Chicago, and colleagues.
That percentage translates into almost six million children in the U.S., the researchers noted.
And among these allergic children, 38.7% had a history of severe reactions and 30.4% were allergic to more than one type of food, they reported online in Pediatrics.
Previous studies have suggested that the prevalence of food allergy among U.S. children ranged from 1% to 8%, with an analysis of data from the 2005 National Health and Nutrition Examination Survey finding a prevalence of 4.2% in children ages 1- to 5-years-old.
These earlier estimates were imprecise and also provided no information on the severity of the allergies, so Gupta's group conducted a cross-sectional survey using a representative sample of households with children.
The sample included 38,480 children, evenly divided between the sexes, with a mean age of 8.5 years.
A total of 56.4% were white, 21.6 were Hispanic, 14.1% were black, and 4.8% were Asian.
Multiple allergies were reported in a total of 2.4% (95% CI 2.2 to 2.6), while severe allergies were found in 3.1% (95% CI 2.9 to 3.3).
Peanut allergy was the most common, present in 2% (95% CI 1.8 to 2.2) of all children surveyed, with milk and shellfish allergy reported in 1.7% (95% CI 1.5 to 1.8) and 1.4% (95% CI 1.2 to 1.5), respectively.
Among children with known food allergies who were surveyed, the prevalence for allergies was highest for peanuts at 25.2% (95% CI 23.3 to 27.1), followed by milk at 21.1% (95% CI 19.4 to 22.8), and shellfish at 17.2% (95% CI 15.6 to 18.9).
Prevalence varied according to age, ranging from 6.3% in children younger than 2 years to 8.6% in those 14 years and older.
Peanut and tree nut allergies most often provoked severe reactions, with symptoms such as anaphylaxis, wheezing, or low blood pressure accounting for slightly more than half of all reactions to these foods.
Severe reactions also were common for shellfish, soy, and fin fish, reported in 46.8%, 42.6%, and 40.6%, respectively.
Multiple logistic regression analysis found increased likelihood of food allergies in Asians and blacks, with odds ratios of 1.4 (95% CI 1.2 to 1.7) and 1.8 (95% CI 1.6 to 2.1), respectively.
However, these minorities were less likely to have been formally given a diagnosis of food allergy, which may reflect disparities in healthcare, according to the researchers.
Odds of allergies also were higher for all older ages groups compared with ages younger than 2 years.
In addition, the chance of having food allergies was greater for children residing in the southern U.S. (OR 1.5, 95% CI 1.3 to 1.7).
However, children living in households with annual incomes below $50,000 were less likely to be allergic (OR 0.5, 95% CI 0.4 to 0.7).
The likelihood of having severe allergies was greater in boys; in children with multiple allergies; in higher income households; and in older age groups (P<0.05 for all).
"Consistent with past reports, this study found that odds of severe food allergy progressively increased with age, peaking at more than twofold higher odds of severe reaction history among children ages 14 to 17 years versus those ages 0 to 2 years," the researchers observed.
A limitation of the study was the possibility of recall bias among participants.
The authors concluded that their findings should "provide critical epidemiologic information to guide strategies for the prevention of food-induced reactions."
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
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