By Dr. Paul Ehrlich
A year ago I wrote a response to a Pediatrics study that seemed to claim black children were at higher risk of food allergies than non-white kids. The WebMD account said, “The study found that African-Americans have a threefold higher risk for food allergies than the general population and that African-American male children had the highest food allergy rates in the U.S., with a fourfold higher risk.” I wrote, “Funny, but after spending at least one day a week for several years in inner-city schools dealing with severely asthmatic children, I saw NO co-morbidity with peanut allergies, which led the Pediatrics list.”
A new article in the Journal of Allergy and Clinical Immunology (JACI) sheds light on this subject that lends credence to both sides, although I must say that it lends more support to my observations than it does to assertions of risk levels. The most important thing it does, however, is provide more ammunition against the methods by which food allergies are generally diagnosed.
Drawing partly on that same Pediatrics study from a year ago, the authors of the new JACI article say, [B]lack participants had significantly higher median values for total IgE, peanut-specific IgE, and hen’s egg white–specific IgE compared with white participants. These findings suggest that black participants might have a higher level of allergic reactivity than white participants.”
Does this indicate a hidden epidemic or an epidemic waiting to happen?
Not according to these authors. “We demonstrate that in a population of high-risk atopic children, black race increases the risk of sensitization as measured based on specific IgE levels but is paradoxically associated with a decreased risk of sensitization to peanut, as measured based on SPT responses, and a decreased risk of likely clinical reactivity to peanut (a wheal diameter >4 mm is defined in our study as likely clinical PA at this age)… This might reflect an evolutionary adaptation toward TH2 responses in the face of high rates of infection with helminths [parasites common in their ancestral homes]. Another possibility is that IgE in black infants is directed against different allergens compared with that in white children or to different epitopes within those allergens. However, it is also possible that this difference between white and black children might not have been observed with other prescreening criteria.”
Okay. I was right. But I’m not going to do an end-zone dance. All I really want to say is that we are still as a medical community doing a lousy job of diagnosing food allergies. Another article in the new JACI says that 30% of parent-reported food allergies have never been diagnosed by a doctor at all! Most of the rest were diagnosed using blood tests and SPTs with oral food challenges in only 20% of cases. I have no doubt that millions of kids are doing without nutritious foods and having their activities needlessly restricted on the basis of alarmingly high food-specific IgE levels that have nothing to do with real allergies. The gold standard is still the double-blind placebo controlled food challenge. The silver standard remains the oral food challenge, which is underused. The bronze goes to judicious use of tests with a comprehensive clinical history. Everything else is an also ran.
Double Dutch by nycitysnaps.com
Food challenge by clinicaladvisor.com