Thursday, July 12, 2012

Pediatricians Cause Food Allergies!

You may have seen media references to a new study out this week: Infant Feeding Practices and Nut Allergy over Time in Australian School Entrant Children

The headlines have been quite sensationalistic:

Children With a Regular Doctor More Likely
To Have Food Allergies!

Seeing The Pediatrician Linked To Allergies

Child Have An Ear Ache? Think Twice About That
Routine Trip to the GP...

I'm sure you've seen these headlines splashed across your various news feeds.


Well, how about these then?

Oh, yeah, those you've seen! 

Here's the thing: the study referenced above actually found a correlation between both things. Children who were nursed exclusively during the first six months of life were slightly more likely to have a nut allergy. About the same level of risk was found for children who regularly visited their doctor

I know news organizations are desperate for controversies that will pump up readership...but this just seems so WRONG and STUPID! Now there will be another round of new mothers afraid of breastfeeding, afraid of peanuts...all because of a study that has, buried in all the biased language, an important line:

Also, the study design does not allow causality to be inferred.

Stop and think beyond the sensationalism for a moment. We KNOW there is a sensitizing agent/experience involved with food allergies. Somewhere along the line, a baby's immune system is encountering proteins to which it develops a response that later becomes a food reaction.

These sensitizing proteins may very well be in breast milk. However, those same proteins may be on Mom's hands after she made that peanut butter sandwich, or inhaled as pollen that has potential for cross-reactive immune mix-ups. They may be trace amounts in baby foods or baby products. There may be some other entire mechanism for sensitization that we do not yet understand.

This study from the early 90's took the issue of sensitization and breast milk on directly. Mothers were asked to avoid milk, egg and fish while nursing. While initially the babies in the avoidance group showed lower levels of IgE antibodies (in other words, sensitization), over time, the avoidance had no effect on whether the babies demonstrated an allergy. (Here's a comprehensive  and far less biased  review of studies related to maternal avoidance of proteins and the effect on food allergies.)

The point is that the set-up for the sensitization is already in place by the time the protein is introduced. Withholding foods probably doesn't prevent an allergy, but simply delays it. And the fear is that, the longer we wait to expose children to foods, the more opportunity the body may have to develop that environment/trigger/mysterious occurrence that leads to sensitization. That's why doctors shifted back to telling moms to eat the peanuts. Keeping them in the diet seems to do less harm overall. Perhaps they advice will shift yet again with this study...but does it really even matter?

The bottom line is: humans have been nursing babies and eating nuts for hundreds of thousands of years and very few of those babies became sensitized. 

Sensitization is not the answer, or really even a large part of the puzzle. The question is why some children become sensitized and why it is happening now, in the last 20 years, in so many children. The protein involved (like peanut) is also not a large part of the puzzle, because the common allergens change as a culture's food changes. We know babies tend to become allergic to foods that have the right molecular weight and allergenic properties that are most commonly eaten by the population into which they are born. 

This study seems to be implying that somehow changing the window of solids introduction from four to six months is enough to tip Mother Nature over into suddenly creating an epidemic of food allergies. Am I the only one that thinks that conclusion is just flat-out stupid?

It's almost as stupid as looking at the data in this study that was JUST AS STRONG in favor of a link between visiting the doctor and food allergies...and concluding that doctors cause food allergies.

But, then, the Mommy Wars don't revolve around doctor visits. They do revolve around the decision to nurse. Easy to see why these publications would focus on one and leave the other behind.

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