Peanut allergies more rife in well-off boys: study
February 9, 2011
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Lesley Ciarula Taylor
STAFF REPORTER
Well-off families produce children with a much higher rate of peanut allergy, particularly in boys, a study of nearly 3 million British patients has found.
At its most severe, a peanut allergy can induce anaphylactic shock and death.
The Toronto District School Board, for example, has a detailed anaphylaxis policy.
The study, published in the Journal of Allergy and Clinical Immunology, also found that the prevalence of peanut allergies is a fraction of what’s been believed.
Still, study author Dr. Daniel Kotz told the Star, the cases of peanut allergies continue to climb.
“Fussy parents” – parents who shield their children from all potential allergens in a hyper-clean environment from before birth – could be one explanation for the higher rate in more affluent homes, Kotz said.
“This needs more research. The hygiene hypothesis is only a hypothesis, one I think it would be very difficult to prove. There are many complex issues involved.”
Researchers studied a newly available database of information from 2,958,366 patients registered with 422 general practitioners in the U.K. from 2001 to 2005.
Young boys were 30 per cent more likely to contract a peanut allergy than young girls were. By age 15, the rate was the same. By age 24, women had a higher rate of peanut allergy than men.
Broken down by income, the rate was 0.7 per 1,000 among higher income children and 0.4 per 1,000 about lower income children, “a significant inverse relationship between prevalence and socioeconomic status.”
The accepted prevalence of all forms of peanut allergy, from mild to severe, has been estimated at one in 100. This study, however, put it closer to one in 1,000.
“The real rate is probably somewhere in between,” said Kotz, once variables such as self-reporting and all allergies lumped together were factored in.
Still, the rate keeps rising. Kotz offered two explanations: “Fewer children outgrow peanut allergy now. And it may be that the diagnosis and recording of the disease has improved.”
A recent article in The New Yorker raised the question: “Could the conventional wisdom on children and allergies be wrong” and examined how the old medical gold standard, of avoiding any exposure ever to potential allergens, might be contributing to the problem.
“The guidelines before with a parent with an allergic condition were, without any hesitation: Get rid of the dog and cat, breastfeed, and don’t introduce any allergic foods,” said Dr. Eric Leith, an Oakville allergist and head of the Canadian Allergy, Asthma and Immunology Foundation.
Now, he said, research has questioned whether such guidelines work for everything.
As for the hygiene hypothesis, Leith said, “It may be higher in the middle class because of their lifestyle. Or do they go to the doctor more? You have to be very careful how you interpret these things.”
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