Pediatric Allergy Theories

Pediatric food allergies are on the rise in the United States, and it may be due to our Westernized lifestyle.

These days, it seems that most kids have allergies to eggs, wheat, milk or nuts. In fact, between 1997 and 2007, pediatric food allergies increased by 18 percent, according to a study published in the journal Pediatrics. In 2007, approximately 3 million U.S. children reported a food or digestive allergy.

In a Journal of Allergy and Clinical Immunology study, researchers found that between 2001 and 2006, visits to the emergency room for allergic reactions at Children's Hospital Boston more than doubled. Moreover, the severity of reactions increased sharply, resulting in more children experiencing anaphylaxis.

Dr. Susan Rudders, the author of the Children's Hospital study, suspects her findings at the local ER reflect a national trend, according to CNN. Though Rudders studied only 1,255 children, her theory is supported by the experience of other physicians across the country. Doctors at the Children's Hospital of Los Angeles and the Children's Hospital of Philadelphia have seen a rise in the severity and number of cases coming into their emergency rooms.

Dr. James M. Rubin, chief of the Division of Allergy and Immunology at Beth Israel Medical Center in New York City, has also perceived a rise in pediatric food allergy cases, though he cautions that it may be due to "better detection on part of parents, pediatricians and primary care physicians."

While nobody is certain as to why there seems to be a food allergy epidemic, theories abound.

Some doctors and scientists wonder if children should be exposed to allergens like nuts and shellfish earlier than age two or three -- the age many doctors recommend -- so that they can avoid developing allergies. In a 2008 study in the Journal of Allergy and Clinical Immunology, researchers found that Jewish Israeli children were far less likely to develop peanut allergies than were Jewish children in the U.K. -- a difference that was linked to with the fact that while 69 percent of Israeli children ate peanuts by the age of nine months, only 10 percent of the British children had.

"In terms of diet, there's a lot of controversy: Should you avoid certain things when you're pregnant? Should you avoid things when breastfeeding or not?" says Rubin.

Another fledgling theory is that a Western diet makes children susceptible to allergies and illnesses. A recent study out of the University of Florence in Italy shows that meat and junk food may make kids prone to allergies. Researchers compared the fiber-rich diets of 14 children from a rural African village in Burkina Faso to the diets of 15 children from Florence. The African kids ate mostly grains, beans, nuts and vegetables that had been farmed or raised near their homes, while the Italian kids ate far more meat, fat and sugar. The scientists found that the African children had flourishing "good" bacteria in their guts -- cutting down their risks for obesity, easing their ability to digest food, protecting against bugs and limiting inflammation. They also had an abundance of fatty acids, which guard against inflammation, asthma, allergic eczema and other allergic reactions.

But it's not just American and European diets that could be the culprits. There's also the popular "hygiene hypothesis," which posits that growing up in a sparkling-clean environment doesn't allow a child's immune system to properly develop. Modern medicine and sanitation have eliminated many infectious diseases but have also limited a child's exposure to immune system-building bacteria, which may ultimately protect a child against allergies, obesity, asthma, inflammatory bowel disease and autoimmune diseases.

"The substance in the immune system that's associated with allergies was put in people to defend them against parasites," says Rubin. "There are no parasites in more civilized environments, so it seems that [the substance] may react to pollen or food." Multiple studies in European rural areas have shown that the children raised on farms have a decreased prevalence of hay fever and allergic rhinoconjunctivitis, implying that growing up in a nonsterile environment can help ward off some allergies.

Ultimately, Rubin believes little can be definitively done to prevent children from developing allergies. Allergies, he notes, are hereditary -- when one allergic person marries another, their odds of having allergic children rise 90 percent. "If they're destined to develop allergies, they will develop allergies," he says. "Can you prevent them from occurring? The answer is no."