MONDAY, Dec. 24 (HealthDay News) -- Many children with food allergies may be bullied at school -- sometimes with potentially dangerous threats to their physical health, a new study suggests.

The study, of 251 families at a New York City allergy clinic, found that about one-third of kids said they'd been bullied specifically because of their food allergy.

The bullying usually happened at school and often took the form of teasing. But in many cases, the children said classmates threatened them with the food to which they were allergic -- waving it in front of them, throwing it at them or saying they would sneak it into their other food.

"With food allergies, that kind of bullying does carry a theoretical physical risk," said Dr. Jay Lieberman, an assistant professor of pediatrics at the University of Tennessee Health Science Center, in Memphis, who was not involved in the study.

Food allergy symptoms can range from hives, swollen lips and stomach pain to potentially life-threatening reactions where children can't breathe and their blood pressure plummets.

In the United States, an estimated 4 percent to 5 percent of kids younger than 18 have a food allergy, according to the American College of Allergy, Asthma and Immunology. A handful of foods, including peanuts, cow's milk, eggs and fish, account for most.

Because parents of food-allergic kids are usually vigilant about avoiding the culprit foods, severe allergic reactions are fortunately rare, said Dr. Eyal Shemesh, the lead researcher on the new study.

"What really affects these children's lives is everything that surrounds the allergy -- the food avoidance, the anxiety," said Shemesh, an associate professor of pediatrics and psychiatry at Mount Sinai School of Medicine, in New York City.

And bullying, apparently, can be part of the "everything" that surrounds kids' food allergies. Children could get stigmatized at school, experts say, when classmates have to, for example, avoid bringing peanuts and peanut butter to school.

Peanuts, even in small amounts, can cause a serious allergic reaction. And simple skin contact with a peanut product can trigger a rash.

Both Shemesh and Lieberman said it's important for parents, schools and doctors to be aware that food allergies can make kids a target for bullying.

The study, reported online Dec. 24 and in the January 2013 print issue of Pediatrics, included families at one New York City clinic -- most of whom were white and upper income. So the bullying rate may not be representative of all kids with food allergies, Shemesh said.

But the results back up a 2010 study that Lieberman worked on. In that one, a similar percentage of kids -- 35 percent -- said they'd been bullied because of their food allergy, with most saying it happened more than once.

This new study, Lieberman said, went a step further by asking kids about their quality of life -- including their emotional well-being and how they were getting along at school. It turned out that children who were bullied reported a lower quality of life than their food-allergic peers who were not targeted.

On the other hand, among kids who were bullied, those who'd told their parents reported a better quality of life.

It's not clear why that was. "I don't know if the parents did something about the bullying," Shemesh said. "I just know they knew about it."

It is always possible that parents called the school or otherwise helped their child. Or, Lieberman said, some kids may have just felt better after talking with their parents.

Whatever the reason, Shemesh suggested that parents ask their children if other kids have ever bothered them about their food allergy.

At the same time, he said, "I don't want to be alarmist. And we are not trying to say that the bullies are 'villains.'"

It may be that kids doing the bullying do not understand how serious food allergies are, Shemesh noted. So it's possible that if they get more education on it, that will put an end to the bullying in some cases.

Education about food allergies -- for kids and adults -- could help, agreed Dr. Mark Schuster, chief of general pediatrics at Boston Children's Hospital.

Parents of classmates, he noted, may unwittingly encourage bullying if they complain because they can't send their child to school with grandma's famous peanut butter cookies.

"When it comes to food allergy, people often roll their eyes," Schuster said. "They think that kids are just trying to avoid a food they don't like. And they may not understand that food allergies can be serious."

Schuster also suggested that parents of kids with food allergies be aware of the possible "clues" that their child is being bullied -- such as not wanting to go to school, appearing down, and complaining of chronic stomachaches or headaches.

More information

Learn more about food allergies from the Food Allergy and Anaphylaxis Network.