Monday, September 23, 2013

Seasonality and Food Allergies

Does it seem to anyone else that the odds of outgrowing a food allergy are a bit of a crap shoot?

The odds seem even, well, odder lately. For example, there's this recent study that seems to promote the idea that kids who strictly avoid are more likely to see resolution of their allergy. What does that even mean, strictly avoid? My son ate next to no processed foods, so I would imagine we were in the "strict avoidance" group. When he was RAST tested as part of the clinical trial, his score was so low he barely qualified. Yet he still reacted to peanut - and now his RAST has climbed back up.

Are peanut challenges as part of these trials a bad idea? If that's the case, though, how does that square with oral immunotherapy and SLIT? What about the kids who are going through the challenges and tolerating peanut? How do doctors ever know when to flip that magical switch from avoid to introduce?

Here's another study of people who outgrew, this time for tree nuts. Some of the kids had experienced severe past reactions, yet they still passed.

Then there was that weird SLIT study earlier in the year, where two of the kids in the placebo group spontaneously saw their peanut allergy resolve. I remember laughing when I got to that section of the write-up. You could tell that the researchers were a little miffed at having to explain the anomaly (and the explanation was basically "hey, we don't know, some kids just outgrow").

Those of us who have kicked theories around for years have hypothesized that there are different types of allergies: some that will be outgrown pretty much no matter what parents or kids do, and those that won't.

But what if there's something altogether different going on here?

I've been fascinated for years by the research that showed kids born in the winter months have a higher incidence of food allergy. This study showed an almost 20% increase in food allergies among fall/winter babies. This one showed an increase of 53%! One hypothesis for this is that when very young babies are exposed to heavy pollen loads, their immune system is more likely to learn to overreact. It's also become pretty clear that Vitamin D is somehow playing a role in this.

Honestly, though, I don't care about any of that. I just want to know how to get my kid to pass food challenges. I'm sure you do as well.'s my theory:

What if passing or failing a food challenge depends on the time of year the food challenge is given?

Think about it. If kids are predisposed to develop food allergies based on their month of birth, then perhaps those same factors are still in play when it comes to the waxing and waning of food allergies.

Based on all this, the best time to introduce a new food to the immune system would presumably be January or February. It would be especially effective if the child's Vitamin D level was high at the time, either through a good summer/fall spent playing outside or supplementation.

Our own personal experience does align with this. My son's final clinical trial challenges (the ones where he did well) occurred in October and January; earlier this year, he passed a soy challenge in February. Would he have passed if we had scheduled it in, say, May? Or would his already-overburdened immune system have gone crazy, re-sensitizing him to soy and undoing all our hard work of avoidance?

The uneven results of many of these clinical trials might also be at least partially explained by the periodicity of testing. It would be fascinating to see the results of the last several studies graphed against the months in which challenges occurred.

If your child has passed a food challenge, was it in the winter? If failed, was it in the spring or summer? Leave me a comment! 

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  1. My son was born in January, by 6 mths it was determined though RAST that he was allergic to milk, eggs and peanuts. He passed a milk food challenge at the age of 4 in the month of July.

  2. Failed milk mid-winter, failed baked milk and peanut in early summer. Yet to pass any challenges. Now he is 5 his allergies show no sign of improvement whatsoever. I would love to find some reasons, keep up your investigations :)

  3. We have never even attempted a food challenge. My son is 6 and was born in June. He's allergic to dairy (has had severe reactions to dairy), eggs, peanuts and tree nuts. We live in FL so he should be getting plenty of vit D from the sun! We will more than likely be challenging his tree nut allergy in Jan, so I hope you are right. Last year his tree nut RAST was neg but the skin test was positive so we avoided for another year and are hoping at his next testing to have a neg skin test too.

  4. My son has been participating in an OIT clinical trial at Stanford. He graduated to maintenance last summer. His skin tests following graduation show a dramatic difference during environmental allergy season (lots of spots, even in areas he wasn't pricked). Having seen really strange skin test results in the spring, I wouldn't personally choose to schedule skin tests during seasonal allergies (unless I was trying to gauge their impact on a person's FA). I have no doubt that the immune system is more taxed and less able to handle food allergies during the peak of seasonal allergies. I would assume this would hold true of the body's reaction to a food challenge as well. After allergy season, his skin tests were clear again by fall.

  5. My son was born in January. He is 20 years old and anaphylactic to milk. He recently failed a baked milk challenge that was done this summer but I suspect he would have failed no matter the season it was given. I have to wonder the purpose to some of these studies... After 20 years they don't seem any closer to the cause nor a cure. The treatment remains the same - avoid the food and for goodness sake, carry your Epi - always!

  6. Child born in April, failed challenge in July.

    Do you think RAST testing would vary according to time of year blood is drawn? Do IgE levels vary by time of year/seasonal allergies? We always do RAST in June, but perhaps we should push it to next winter instead of the summer this coming year. I wonder if the results would be different. It would sure be nice to not see RAST result other than >100!

  7. I definitely think RAST varies, depending on what time of year. However, most people take their kids to the doctor once a year. That's what I tried to point out in this article - there may be windows of opportunity with this stuff.

    However, wild swings in RAST may be because the allergy that's showing up is actually a pollen allergy. While my son was part of the clinical trial, they were drawing blood every three months and did a couple for hazelnut (because, at the beginning, they thought they might use that as the allergen, instead of peanut). After the trial, we had one done in the winter. The results were pretty different. The doctor looked at the numbers and agreed with my assessment that the hazelnut (which just sprang up in the last couple of years) is probably a pollen cross-allergy. I suggested a uKnow for hazelnut and she said "let's just challenge him." So...we'll be going back for a hazelnut challenge at some point this winter.

    For true allergies? Who knows! But researchers cannot explain how or when some kids spontaneously resolve, and those two kids in the peanut study were older than eight. Maybe there are simply times where, if you slip in an allergen, the immune system allows it.

  8. I would caution against choosing a time of year for testing just so you might see lower RAST scores. Your hypothesis that the immune systems are on overload during the peak of seasonal allergies is intriguing. However, there are a lot of other variables, including indoor allergies (mold, dander, etc.) that could be contributing, hence the huge statistical variation.

  9. Hi! I've just stumbled across this blog while looking for something else but it caught my eye cause my son has multiple food allergies. We recently took him to a dietician who thinks that he has leaky gut and suggested we put him on the gaps diet to try to heal his gut lining. Anyway, I was just thinking that maybe some kids outgrow allergies because their diet includes healing foods that allow their bodies to repair, while others not so much? And the time of year may be a factor because we tend to eat more of the nourishing foods like soups and stews and animal fats in the colder months. Just a thought :-)


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