THE BLOG
10/29/2010 08:45 am ET Updated May 25, 2011

Child Food Allergies: What Causes Them?

Like any good mother, ever since my son Eden was diagnosed with life-threatening food allergies, I've been trying to find out why. The Hygiene Hypothesis is a popular theory for the increase in food allergies. In 2004, the National Institute of Allergy and Infectious Disease followed the medical records of 835 children from birth to age one, documenting any fever-related episodes. At six to seven years old more than half of the children were evaluated for their sensitivity to common allergens such as dust mites, ragweed and cats. Of the children who didn't experience a fever during their first year, 50 percent showed allergic sensitivity. Of those who had one fever, the percentage dropped to 46 percent. But of the children who had two or more fevers only 31 percent showed allergic sensitivity.

So does this mean that children might have fewer allergies if society allows them to get dirtier and sicker? But how much sicker? What about the advances modern medicine has made in eradicating childhood diseases like Polio? And how much dirtier? Do we want our children exposed to more parasites? The Helminthes Hypothesis is nearly identical to the Hygiene Hypothesis but it focuses exclusively on parasites. Helminthes are the worms that live in the human intestinal tract.

In the 1980's researchers studied Venezuelan Indians and discovered that within those who lived in the rainforest and were also heavily infected with worms only 10 percent had allergies. But among the wealthier Venezuelan Indians who lived in cities and were only lightly infected with worms, 43 percent had allergies. A "Worm vs. Wealth" theory is the Yang to the Yin of the Hygiene Hypothesis: Maybe we need more exposure to parasites to balance our reduced exposure to bacteria and viruses. Either way, clean water and food, antibiotics, reduced exposure to parasites, animals, viruses and infectious diseases may have caused our progressive worldwide allergies. But these ideas don't offer obvious solutions to parents. A few years ago, a well-known research immunologist injected himself with hookworms and reduced his allergic symptoms (shudder).

While there isn't strong evidence suggesting that an allergic child would benefit from exposure to his allergens or, say, from an occasional lick of a New York City subway pole (dramatic shudder), when people ask me why Eden has allergies and I answer, "Well, most doctors favor the Hygiene Hypothesis," their next question predictably involves hand wipes. How to segue towards the less inviting explanation, "Well, some scientists believe our world is too clean!" Hmmm? Sure, then I could then launch into a monologue about contaminated water except my own kitchen counter is never without a full pitcher of filtered water with its reassuring "filter-change-reminder-sticker."

My friends are open to switching their hand soap to Burt's Bees All Natural, but balk at the idea of unfiltered water and unwashed hands. Some parents ask me, "What about all those pesticides? I only buy organic! Don't you?" Well, no, not always. Neither of my children's diet is organically stellar. But I get it. I want to control my children's health too. I want to benefit from medical progress while circumventing nature's backlash. And the hard truth is if I had let Eden play in the mud like a baby farm animal, he still may have gotten allergies. Medical theories address trends and individuals are complicated by their genetics and the particular circumstances of their lives.

Other allergy theories abound. The increased pediatric vaccination schedule has been called out as a culprit in causing the increase in food allergies. Perhaps vaccination has led to overstimulation of the immune system? Perhaps the ingredients in vaccinations produce a delayed allergic response? Other voices speak out against our industrial and agricultural practices. Perhaps pesticides, cross breeding and genetic engineering are responsible for our children's "toxic overload."

Perhaps all those alterations to our food render it unrecognizable to our digestive tract? Every factor from cooking methods, socioeconomic status, gender, exposure to pool chlorine, fetal head size, early exposure to foods, late exposure to foods, country of birth origin has been examined in terms of its contribution to food allergies. While some of those circumstances have proven to be instrumental, none have been proven to be the sole determining factor.

Meanwhile I've listened to many mothers assume the burden of their children's allergies by citing their maternal diet. Yet an expecting mother's diet hasn't been proven to cause their children's food allergies. We parents want to know why things happen to our children. We are ready to bear the guilt. Bring it on! You can't handle the guilt! I can! When Eden was born he was given antibiotics to clear excess fluid from his lungs. The NICU doctors advised us to permit it. They said it was probably best. Was that it? Did those antibiotics tip Eden's first domino?

Ah. But then there is guilt's evil twin -- blame. In 2008, six years after my first pediatrician insisted that Eden wasn't vomiting incessantly and allergically to his milk-based formula, the American Academy of Pediatrics published a report defining Eden as an infant at risk based on our family history of allergies. Under those guidelines my pediatrician would have been obligated to instruct me to use "an extensively hydrolyzed formula" without question. (Again, she did not.) When I think about that AAP report many times I swallow a raw and unending frustration. Was that it? Then again, Eden was vaccinated on the recommended schedule while his food allergies were emerging. Was that it?

Maybe allergy parents think we gave our children the wrong food or too many antibiotics. Maybe we wake up in the middle of night wondering if we should have kept them away from the cats or the peanut proteins we leaked through our breast milk. Maybe we did something bad that was supposed to be good for our children. But as the medical community looks for answers, I continue to look for ways to help my son live well -- odds I can control.