Investigating potential adult FPIES food reaction

Preface: I’m writing this up following discussion in our Thursday self research chat, because I’d like to document something I’ve investigated and might continue doing so.

I’ll start with a description of the issue I had, and add a couple posts about a couple stages in my investigation so far. If there are additional incidents or things I learn, I’ll be able to post more here.

Unexpected incidents

March 31: About three hours after dinner, I was woken up by nausea and stomach pain. I had to vomit. I checked others that had eaten the same foods, and they felt fine. The pain continued a bit, and I vomited again – no other symptoms, and it had me worried I was experiencing another kidney stone – but it subsided and I fell back asleep.

April 24: It unexpectedly happened again, same symptom pattern: stomach pain and vomiting about three hours after dinner, which subsided. No other symptoms (fever, etc. like stomach flu), nobody else affected.

Suspected reaction to Impossible Burger

Comparing the two events, a common item in both meals was Impossible Burger. I strongly suspected this was the cause. Also, I thought the reaction might be Adult FPIES (Food-Protein Induced Enterocolitis Syndrome).

May 5: I cooked and deliberately ate an Impossible Burger patty again (about 4oz). I recall experiencing pain and nausea after this, but there was no vomiting.

I was, at this point, convinced that Impossible Burger was to be blame.

Specifically, I wondered if Soy Leghemoglobin – a protein food additive isolated from yeast that are engineered to produce it – was to blame. The Leghemoglobin in Impossible Burger is isolated from soy, but is only expressed in root nodules, and so it is not normally present in foods derived from soy bean (which I haven’t had an issues with). It’s unique to Impossible Foods and so I was very suspicious of it.

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Contacting Impossible Foods

At this point, I was interested in trying Soy Leghemoglobin directly to see whether it triggered a reaction, rather than wondering about all the ingredients on the list.

In response, Impossible Foods’ food safety team asked me to complete a questionnaire regarding the incidents:

I also asked whether it would be possible to acquire the Soy Leghemoglobin ingredient itself, so I could test it specifically.

Impossible Foods responded that follow-up should be with a clinician – and allergist – and I should not be engaging in testing this myself.

I contacted a specialist group and scheduled an appointment, but the earliest availability was July 29.

Frustrated with the slowness of this process, I created a spreadsheet trying to determine what other ingredients might be an issue (potato protein?). This compares Impossible Burger ingredients against the ingredients in three other “fake meat” products I’ve eaten regularly without issue:

I was able to use food documented in Open Food Facts here:

Regarding potato protein: according to the food label the amount in Impossible Burger must be less than 2%. So 4oz (113.4g) of patty would be a maximum of about 2.3 grams. A medium potato has about 4.3g protein, and I’ve eaten potatoes recently without issue, so I think it’s unlikely a trigger.

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Testing Impossible Burger again.

I became concerned that my third incident – and only deliberate test of Impossible Burger – felt ambiguous. Had I imagined the pain and nausea? Especially because I was already suspicious and anticipating a reaction (unlike the previous two events).

So, despite being advised against testing ingredients myself, without clinical oversight, I went ahead with another food challenge on May 25.

This time, I decided to log the process in a document as it occurred, recording the time and any symptoms I was experiencing.

The result: no reaction.

Impossible Burger does NOT appear to trigger any reaction.

And now a bit of wrap-up (for now, at least)…


What I learned…

  1. I can imagine symptoms. As my May 25 log shows, anticipating a reaction caused heightened awareness of potential symptoms. I became very aware of my skin, which felt flushed, numb, and tingly – all potential “allergic reactions”. (I did also note that it was a warm day, and I might just be sweating and anxious.) My test on May 5 now seems likely to have been imagined symptoms as well.

  2. I proved myself wrong (and I’m glad I did). My belief that Impossible Burger was causing this was very high. Not merely intellectually, but viscerally: I gagged while eating it, and had to wear a nose plug. (As noted in my write-up about the first three incidents, I’d eaten this food in the past without issue.) But I was concerned that my May 5 test may have been psychologically induced symptoms, and I was going to potentially unfairly malign Impossible Burger without being 100% sure. So I pushed myself to test again. Falsifiability is a core feature of science: this was a falsifiable belief, and I falsified it.

  3. It’s something else. At this point… I don’t know even know whether these events were caused by food triggers. An incident may never happen again, and it will remain a mystery forever. (But if it does, I’ll have more data.) In the meantime I’m trying to look into what other ingredients were present in the two “real” incidents to see if there are any other suspects, both of which involved meals prepared by restaurants.

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Maybe you have gained immunity against Impossible Burger? :grin:

@ejain Or regained immunity :joy:

I documented in the write up of March/April/May incidents… I consumed it previously, including twice in March. (Doordash records helped reconstruct that retrospective information!) Since FPIES can develop suddenly / spontaneously, that didn’t disprove it… I suppose, one must get exposed for antibodies to develop.

Now it’s nearing mid-June and I haven’t had any new incidents. :man_shrugging: I didn’t hear back from a restaurant I reached out to. One thing I haven’t tried … I can try eating the exact same order from Rubio’s. :grimacing:

I think I should probably try that. Either way I learn something. If the vomiting reaction isn’t reproduced, I’ll have learned … I have no idea what happened, and maybe I never will.

Stay tuned I guess. :see_no_evil:

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