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Why Allergies Are On The Rise


Allie Lemco Toren

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What I Tell Parents About Treatment for Anaphylaxis

Knowing your child is at risk for anaphylaxis is stressful. But you can be prepared.

It’s difficult to ignore the recent prevalence of allergies in the United States today. Gone are the days of swapping lunches in the school cafeteria and munching on salty airline peanuts. Today’s world is full of allergy alert bracelets and nut-free, wheat-free, dairy-free, egg-free cookies. These changes are necessary, since up to 15 million Americans have food allergies today. In fact, food allergies affect 1 in 13 children under 18 years old: that’s an average of two kids in every classroom. And that number keeps rising—a 2013 study by the Centers for Disease Control and Prevention (CDC) showed that the number of American children with food allergies jumped about 50% between 1997 and 2011.

Although this change may partially result from more children seeing allergists and receiving a diagnosis than in the past, that’s still a staggering leap. Of course, food isn’t the only culprit causing allergies—almost 8 million children in the United States experience respiratory allergies, and almost 9 million children suffer from skin allergies. Many children outgrow their allergies, but some struggle with them for the rest of their lives.

So what’s going on?

That’s the same question researchers are asking. Unfortunately, we’re not quite sure what’s causing this allergy epidemic. But we do have some promising theories, and researchers are closer than ever to cracking the code.

Anaphylaxis can be frightening, but being prepared will help you feel empowered to prevent a dangerous allergic reaction. Do you know all the facts?

Medical Reviewer: William C. Lloyd III, MD, FACS Last Review Date: Nov 6, 2015

2017 Healthgrades Operating Company, Inc. All rights reserved. May not be reproduced or reprinted without permission from Healthgrades Operating Company, Inc. Use of this information is governed by the Healthgrades User Agreement.

The Hygiene Hypothesis

Although this surge in allergies seems like a new phenomenon, the leading theory behind it was actually first proposed in 1958—but it’s more relevant than ever today. In a nutshell, the hygiene hypothesis theorizes that we’ve become too clean for our own good. The thought is, although our Western anti-bacterial lifestyles help us to avoid infections (great!), the bacteria we’re killing or avoiding are instrumental in training our immune systems to differentiate between harmless and harmful irritants (not so great). Without these helpful bacteria, our bodies become hyper sensitive to foreign particles, and react accordingly—causing allergic reactions that sometimes include life-threatening anaphylaxis.

The hygiene hypothesis leaves us with a lose-lose outcome: in effect, it’s like saying, “bacteria: can’t live with them, can’t live without them.” By using anti-bacterial soaps, decontaminating our water supply, pasteurizing and sterilizing milk and other food products, vaccinating against childhood infections, and using antibiotics, we’re protecting ourselves against life-threatening infections like hepatitis A and childhood diarrhea. These infectious diseases still chronically affect countries where high health standards don’t exist. But on the other hand, the number of people with allergies in those countries is very low. And researchers have found that when those countries put measures in place to eliminate common infections, the rate of allergic diseases rapidly increases.

But there is hope: studies have shown that children who grow up on farms develop fewer allergies, possibly because being around farm animals exposes these kids to more germs, which help their immune systems learn what to attack and what to accept. So, while your instinct may go against letting your toddler crawl around in a barn, it turns out it might be the best thing for him. And a recent 2015 study revolutionized the way we think about food allergies—researchers found that introducing peanut-based products to infants actually prevented them from developing an allergy to peanuts. This finding goes against the prevailing theory that early introduction of allergens actually increases the risk of developing an allergy. Essentially, exposing young kids to allergens has been shown to help strengthen children’s immune systems—not weaken them.

A Gut Feeling

In the same vein of the hygiene hypothesis comes the theory that the decrease in specific bacteria found in our gastrointestinal tracts is related to the increase of allergic conditions in our society. Because of a variety of factors, like our super-hygienic environments, the rise in cesarean section (C-section) births, and the increase in antibiotic use, children are less exposed to gut microorganisms, which are thought to help the immune system develop. In a natural birth, an infant’s digestive tract picks up microorganisms from the mother; these microorganisms set off a complex order of events that drive the healthy regulation of the baby’s immune system. However, children born by C-section skip this part, which may lead them to develop allergies.

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Medical Reviewers: William C. Lloyd III, MD, FACS Last Review Date: Jun 17, 2016

© 2016 Healthgrades Operating Company, Inc. All rights reserved. May not be reproduced or reprinted without permission from Healthgrades Operating Company, Inc. Use of this information is governed by the Healthgrades User Agreement.

View Sources

Medical References

  1. Food Allergy Facts and Statistics. Food Allergy Research and Education (FARE).
  2. Increasing Rates of Allergies and Asthma. American Academy of Allergy, Asthma and Immunology.
  3. Why Has There Been an Increase in Food Allergies?
  4. Blaser M. Antibiotic overuse: Stop the killing of beneficial bacteria. Nature. 2011;476:393-394.
  5. Why Is Allergy Increasing? Allergy UK.
  6. Ma L, Danoff T, Borish L. Case fatality and population mortality associated with anaphylaxis in the United States. The Journal of Allergy and Clinical Immunology. 2014;133(4):1075-1083.
  7. Marked Increase in Anaphylactic Shock Hospitalization Rates. American Academy of Allergy, Asthma and Immunology.
  8. Branum A, Lukacs S. Food Allergy Among U.S. Children: Trends in Prevalence and Hospitalizations. NCHS Data Brief, no 10. Hyattsville, MD: National Center for Health Statistics. 2008.
  9. Death From Anaphylaxis Is a Reassuringly Unusual Outcome. American Academy of Allergy, Asthma and Immunology.
  10. WAO White Book on Allergy. World Allergy Organization.
  11. Okada H, Kuhn C, Feillet H, Bach J-F. The ‘hygiene hypothesis’ for autoimmune and allergic diseases: an update. Clinical & Experimental Immunology: The Journal of Translational Immunology. 2010;160(1): 1-9.
  12. Ober C, Tao TC. The Genetics of Asthma and Allergic Disease: A 21st Century Perspective. Immunological Reviews. 2011;242(1): 10-30.
  13. Du Toit G, Roberts G, Sayre PH, et al. Randomized trial of peanut consumption in infants at risk for peanut allergy. New England Journal of Medicine. 2015;372:803-813.

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