Peanut allergy can be a life-long allergy affecting about 2 percent of the population. Peanut allergy is the most common cause of death due to foods, according to the Asthma and Allergy Foundation of America.

Anyone who packs Junior's lunch has by now heard that peanuts are often a no-no. In fact in many schools, peanut butter and nuts of all kind are all prohibited. Even home-baked goods are banned for fear they might contain traces of nuts.

The hysteria itself is nuts, and in fact the bans may worsen the very problem they aim to address, Nicolas Christakis from Harvard Medical School argues today in BMJ Online, published by the British Medical Journal.

"Measures to control nuts are instead making things worse in a cycle of over-reaction and increasing sensitization," Christakis writes. He calls the prohibitions part of a "mass psychogenic illness" (what used to be epidemic hysteria) "involving otherwise healthy people in a cascade of anxiety."

Growing problem

Among children and teenagers, food or digestive allergies increased 18 percent between 1997 and 2007, the U.S. Centers for Disease Control and Prevention announced in October. Roughly 4 percent of the U.S. population now suffers some food allergy. Most outgrow these by adulthood.

Nobody knows why the number is growing, but some researchers speculate that as other threats to the human immune system are removed from the playing field by antibacterial soap and other modern techniques, the immune system needs something to do, so it attacks the offbeat proteins in peanuts and other foods that many people are known to be sensitive to. In a nutshell, as explained in an article in The New York Times this week, the latent potential for a particular allergen becomes manifest, the thinking goes.

Other studies have generated mounting evidence that this is true for other types of allergies. Avoiding germs can prevent the spread of disease, but too much cleanliness seems to breed more allergies.

"We’ve developed a cleanlier lifestyle, and our bodies no longer need to fight germs as much as they did in the past," Marc McMorris, a pediatric allergist at the University of Michigan Health System, said last year. "As a result, the immune system has shifted away from fighting infection to developing more allergic tendencies."

School charade

Meanwhile, the efforts to make schools nut-free and therefore safe is a charade, Christakis says.

For starters, he calls it a gross over-reaction to the magnitude of the threat. About 3.3 million Americans are allergic to nuts, according to the CDC. More are allergic to other foods, from milk to wheat; about 6.9 million are allergic to seafood. Serious allergic reactions to foods — all foods — cause roughly 2,000 hospitalizations a year and about 150 deaths among children and adults combined.

Christakis compares this to automobiles, which kill some 45,000 a year, and sports, which send about 10,000 children to hospitals each year with traumatic brain injury. Nobody is clamoring to ban cars or sports, he points out.

Also, "there is no scientific evidence that the particular restrictions being imposed are effective or that they warrant the costs incurred," Christakis points out.

Making matters worse

There is evidence, however, that avoiding nuts makes children ultimately more likely to be allergic to them. A study of 10,000 children in the UK, reported earlier this year in the Journal of Allergy and Clinical Immunology, found that early exposure to peanuts reduces the risk of peanut allergies.

"The wholesale avoidance of nuts contributes to the problem by resulting in children who, lacking exposure to nuts, are actually sensitized to them," Christakis said.

He acknowledges that nut allergies can be serious, and that "reasonable accommodation" should be made for those few children known to have serious allergies.

However, "well intentioned efforts to reduce exposure to nuts actually fan the flames, since they signal to parents that nuts are a clear and present danger," he writes. "This encourages more parents to worry, which fuels the epidemic. It also encourages more parents to have their children tested, thus detecting mild and meaningless 'allergies' to nuts. And this encourages still more avoidance of nuts, leading to still more sensitization."

This article is from the LiveScience Water Cooler: What people are talking about in the world of science and beyond.