Nut and peanut allergies may be getting more common in children, doubling over the past five years in the United States, researchers reported on Tuesday.
Canadian researchers said they were seeing many more cases of peanut allergy than expected, too.
Two reports published in the December issue of the Journal of Allergy and Clinical Immunology suggest that peanut and tree nut allergies, which can be deadly, will continue to become more common. This is bad news for such children as peanut products are found in a wide range of food and other products.
"This study confirms what we've been hearing from growing numbers of families, school administrators and other institutional leaders -- food allergy is increasing," said Anne Munoz-Furlong, founder and chief executive officer of the Food Allergy and Anaphylaxis Network.
"This is a public health and food safety issue that affects all of us," she added in a statement.
Peanut allergies affect an estimated 1.5 million Americans and 200 people die every year from severe allergic reactions, called anaphylactic reactions, to peanuts.
The American Academy of Allergy, Asthma and Immunology says there could be several reasons that peanut allergy is becoming more common.
Roasting peanuts can make them more likely to cause an immune reaction, more children may be eating peanuts when their immune systems are immature, and many more skin ointments now contain peanut and nut products.
In 1997, Dr. Scott Sicherer and Dr. Hugh Sampson of the Mount Sinai School of Medicine in New York found that about 1.4 percent of all Americans had an allergy to tree nuts or peanuts.
In 2002, they surveyed 4,855 households representing 13,493 people by telephone, asking them for information about peanut and tree nut allergies.
The numbers of people saying they were allergic to peanuts did not change -- but many more reported their children were allergic. Overall, 0.4 percent said they had a child with a peanut or tree nut allergy in 1997 but 0.8 percent said they had an allergic child in 2002.
"Because this allergy typically develops in childhood and is infrequently outgrown, one might predict that a growing number of the general population will have these allergies," they wrote.
In a second study, Dr. Rhoda Kagan of McGill University and colleagues surveyed 4,339 schoolchildren in Montreal. They found 1.5 percent of the children in kindergarten through third grade -- between the ages of 5 and 10 -- had nut allergies.
"Based on these facts, one could predict that the number of peanut and tree nut allergies may grow larger over time," the American allergy academy said in a statement.
Allergies to peanuts or any other food occur when the body's immune system mistakenly sees compounds from the foods as invaders and creates antibodies to fight them.
Scientists estimate that between 6 million and 7 million Americans suffer from true food allergies. There is no cure and sufferers must often avoid even the tiniest amount of the offending food.
Some recent studies have suggested that 20 percent of children may outgrow their allergies, and many teams are working on vaccines that may help.
Sicherer's survey found that 74 percent of children and just 44 percent who had severe allergies had asked for medical help. Of those who did seek medical treatment, fewer than half were prescribed self-injectable epinephrine -- which can save a life during a severe reaction.