Monday, November 10, 2008

Another Study, Another Contradiction

Yet another study about peanut allergies has been published this week, and this one just adds to the confusion. Welcome to the non-exact science of food allergies!

The October 2008 issue of the Journal of Allergy and Clinical Immunology has published an article detailing a study in which Jewish populations in the United Kingdom and in Israel were compared. They used Jewish subjects in both countries to try to level the playing ground between the two groups as much as possible, with both groups sharing similar genetics and social and economic backgrounds.

In the U.K., mothers are advised to avoid peanuts while pregnant and nursing and to avoid feeding their infants peanuts, so at nine months of age, only 10% of the U.K. children in the study there were eating peanuts. In Israel, there is no such recommendation, so 69% of Israeli children were eating peanuts. What they found is that 1.85% of children in the U.K. have peanut allergy, while in Israel, only 0.17% of the children have peanut allergy.

In other words, in the U.K., where mothers limit children’s exposure to peanuts, kids were ten times more likely to have a peanut allergy than in Israel.

Now what?

The conclusion many people will leap to is simple – early exposure to peanuts is GOOD for you! But is it really? Other studies have shown that early exposure INCREASES the rate of peanut allergy. As so often happens, scientific studies are contradicting each other, and no one understands why.

Many of us who have children with peanut allergies would question this finding, at least from our own experience – I ate peanut butter sandwiches throughout my pregnancy because it was one of the few foods I could stomach during those nauseating months, and yet my son reacted the first time I let him have a bite of peanut butter. If early introduction should have prevented his allergy, all those sandwiches I ate when I was pregnant should have made him a little peanut-eating superman. On the other hand, he was over a year old when I gave him that sandwich, so maybe if I’d given him peanut butter when he was 4 or 5 months old… who knows?

The authors recognize that one study such as theirs cannot be used to reverse current recommendations. In fact, the study says more “randomized controlled interventional studies…are therefore required to determine whether peanut avoidance or the early dietary introduction of peanut will prevent [peanut allergy]. Until such evidence is obtained, current recommendations should remain unchanged.”

Human beings love simple answers. We like one-to-one correspondences. We like to find a direct line between two points. And it really, really makes us mad when we find a nice, straight line, and then someone has the audacity to point out that our straight line falls apart when the end-points are moved around a bit.

So although the study used two groups of Jewish children, all the variables weren’t controlled. What environmental chemicals are used in the U.K. that aren’t used in Israel? What other foods are frequently given to Israeli children that could be providing a kind of protection that U.K. kids aren’t eating? Do both groups have the same chemicals in their drinking water, in their cooking utensils, in their bread? What medicines do the children in each group receive? How long are they nursed?

There are thousands of variables involved when it comes to analyzing the human body chemistry, and I don’t envy scientists the job of sorting them all out as they wage this ongoing battle against food allergies. But I salute them and cheer them on.

I don’t know what to think about this new study. I don’t know that I believe early introduction will save children. I don’t know that I DON’T believe it.

But I do believe that the more studies like this that are performed, the closer we’ll get to understanding what is going wrong inside our bodies. It won’t be easy – when our bodies decide a nutrient is a poison, something outside the boundaries of logic is at work, and it will require thousands of different scientific minds thinking in thousands of different directions before we round up enough points to show us that the lines are really connecting in a meaningful way.

I’m glad this study has been published – not because I want to see a new push for early introduction of peanuts, but because I want to see another group of scientists say, “What? Is that true?” and dig into their own new study to verify, contradict, or more likely, cast more confusion on this conclusion. That’s the only way we will advance this frustratingly non-exact science of food allergies.

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