Peanut allergy epidemic may be overstated
By Dr. Darshak Sanghavi
My son had his birthday party recently at an indoor play space, and a sign there got me thinking. Peanut-containing foods were prohibited ”due to the increased incidence of peanut allergies.”
Anxieties about peanut allergy are understandable — the condition can be deadly — and some concerned parents today support banning peanut-containing foods from public places.
But the medical research suggests that severe peanut allergies are not as common as people think and are surprisingly difficult to diagnose accurately. And although, as a parent, it may seem that peanut allergies have reached epidemic proportions, the evidence is surprisingly thin.
True allergies result when the immune system mistakes innocent substances — like dust, pet dander, and food proteins — for harmful invaders. Almost a century ago, the scientist Carl Prausnitz injected his skin with blood from a colleague allergic to fish and got hives at the injection sites upon eating fish. Later, scientists realized that blood from allergy sufferers contains an antibody called IgE, which erroneously attracts friendly fire from the immune system and can cause runny noses, red eyes, wheezing, hives, and, rarely, shock and death.
According to Anne Munoz-Furlong, a researcher and the founder of the Food Allergy and Anaphylaxis Network, an advocacy group, today about 25 percent of parents believe that their children have food allergies, although only about 4 percent really do. A parent may suspect one after a few spit-ups or a screaming fit following a new food. Yet these are rarely true allergies. And even among children with true allergies caused by harmful IgE, only a tiny fraction will have life-threatening reactions, called anaphylaxis.
While food (and, particularly, peanut) allergies make headlines — like the Canadian teen who died last November after kissing her boyfriend who’d eaten a peanut butter sandwich — the Archives of Internal Medicine in 2004 reported that the average person’s chance of food-induced anaphylaxis is about 4 in 100,000 per year. Roughly the same number of Americans each year die from lightning strikes as from peanut allergies.
A well-publicized household telephone survey published last year in The Journal of Allergy and Clinical Immunology suggested that rates of peanut allergies among children had doubled from 0.4 percent of the total population to 0.8 percent between 1997 and 2002. But the data were not verified by allergy tests, and it’s not clear whether the numbers are meaningful. In the families surveyed in 2002, the rate of peanut allergies among children under 5 was essentially the same as the rate among 6- to 10-year-olds, indicating no sudden increase in allergic youngsters.
The only similar study of peanut allergy using clinical testing and not surveys occurred in Britain’s Isle of Wight and found an increase from 0.5 percent to 1 percent of all children from 1989 to 1996. However, the study was small, and the authors said the difference was not ‘’statistically significant”; in other words, the difference might be due only to chance.