Food sensitivity and intolerance may be mistaken for allergic reaction, even by doctors
By Amy Norton
MONDAY, July 24, 2017 (HealthDay News) -- Many people misunderstand what food allergies are, and even doctors can be confused about how to best diagnose them, suggests a new report from the American Academy of Pediatrics.
It's common for people to think they have a food allergy, but the reality may be different, said Dr. Scott Sicherer, the lead author of the AAP report.
"If you ask someone on the street if they have a food allergy, there's a good chance they'll say 'yes,' " said Sicherer, who heads pediatric allergy and immunology at Mount Sinai Hospital in New York City.
But a true food allergy involves an immune system reaction against a particular food, he explained. Just because you think a food upsets you, that doesn't mean it's an allergy, Sicherer said.
And it's critical to distinguish an allergy from other "adverse reactions" to food, he stressed.
"Some people may have an intolerance, such as lactose intolerance," Sicherer said. "Sometimes it's a reaction due to food poisoning. Some people may just have a hard time eating a big meal."
Food allergy symptoms range from mild (hives and stomach cramps, for instance) to a life-threatening reaction called anaphylaxis -- which can impair breathing and send the body into shock.
People with true allergy need to avoid the problem food, and possibly carry an auto-injector of epinephrine (EpiPen) in case they suffer a severe reaction.
That's a burden, and an expense, Sicherer pointed out. So having an accurate diagnosis is key.
However, even some doctors don't know how to best diagnose food allergies, according to the AAP report. In one study of primary care doctors, 38 percent mistakenly said that skin-prick tests or blood tests are enough to definitively diagnose a food allergy.
The problem is that people can test "positive" for certain allergy triggers on those tests, Sicherer said, but not really have symptoms when exposed to the substances.
The "gold standard" test is a food challenge, which is done by an allergy specialist. There, a patient ingests small amounts of a suspect food over a period of time to see if an allergic reaction occurs.
But, Sicherer said, a food challenge is not always needed: Context matters.
If a child (or adult) has a history of symptoms that clearly point to a culprit food -- and a skin or blood test is positive for that allergen -- then that's enough for a diagnosis, Sicherer noted.
Besides the need for better diagnosis, the report calls for more education on prevention.
At one time, allergy experts believed that young children could be protected from food allergies by delaying the introduction of peanuts, eggs and dairy into the diet.
According to Dr. Bruce Lanser, director of the pediatric food allergy program at National Jewish Health, in Denver, "That advice is absolutely out the window now."
In fact, the latest guidelines suggest something that might sound counterintuitive: Babies at increased risk of peanut allergies should be given peanut-containing foods as early as 4 months of age.
That, of course, has to be done in an age-appropriate way, Lanser stressed. A little smooth peanut butter could be mixed in with breast milk, for example.
Why does that help? According to Lanser, early exposure to peanuts the natural way -- through the gut -- may allow the immune system to work up a tolerance.
Sicherer had some general advice for parents: "If you suspect your child has a food allergy, talk to your pediatrician. Don't just make assumptions."
And remember that skin and blood tests aren't the whole story, Sicherer noted. Your pediatrician should have a "thorough conversation" with you about your child's symptoms, he said.
It might be necessary to see an allergy specialist for a diagnosis, both Sicherer and Lanser said. And if the diagnosis is made, a specialist should be involved in your child's care, they advised.
How common are food allergies? It's hard to pin down, according to the AAP. Since studies on food allergy prevalence are often based on people's self-reports -- or have other limitations -- it's not clear how reliable the figures are.
Based on recent research, Sicherer said, anywhere from 2 percent to almost 10 percent of U.S. adults -- and up to 8 percent of children -- may have a food allergy.
A short list of culprits accounts for nearly all food allergies, according to the American College of Allergy, Asthma and Immunology: Cow's milk, eggs, peanuts, tree nuts, seafood, wheat and soy.
The report, published July 24 in Pediatrics, highlighted issues brought up in a recent analysis by the U.S. National Academies of Sciences, Engineering and Medicine.
The American College of Allergy, Asthma and Immunology has an overview of food allergies.
SOURCES: Scott Sicherer, M.D., professor, pediatrics, allergy and immunology, and division chief, pediatric allergy and immunology, Icahn School of Medicine at Mount Sinai, New York City; Bruce J. Lanser, M.D., assistant professor, pediatrics, and director, pediatric food allergy program, National Jewish Health, Denver; July 24, 2017, Pediatrics, online
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