I chose to test corn partly because it was easy to find a good placebo: I don't have an allergy to arrowroot starch, and it looks the same as corn starch, and has similar solubility in water. Also, my corn allergy means that most tablets make me sick, since they contain corn starch or other corn products. So I have to get a lot of medications made by a compounding pharmacy, and they aren't covered by my insurance. So it would be very disorienting and embarrassing, but also quite wonderful, if I found out that I had imagined my corn allergy. My allergies to other foods cause me a great deal of trouble too.

I got 4 identical opaque white plastic containers, and labeled them on the bottom, one as the allergen and the other 3 as placebo. I started out testing myself with just 5 mg of corn starch, in a water solution. That small an amount doesn't show up in the water solution, so I used containers with just plain water as the placebo in the beginning.

I randomized the vials in a microwave for a 3 minutes and an arbitrary number of seconds, on the lowest power so they wouldn't get hot. I went away while the microwave was running. Then I took the vials out of the microwave one by one with my eyes closed, and put them in the fridge.

I consumed the vials one by one on different days, being careful to keep the bottom out of view as I poured the contents into some food. I also did my best not to look at the contents of the vials as I poured them out. I put a tag with which day it was inside the vial, closed the top, and put it into a box, being careful to shield the bottom of it from view. Then I noted down my reactions in a log file. At the end of the 4 vials, I wrote down my guess as to which day I'd gotten the allergen, and I compared my guess with which day I'd actually gotten it.

If I felt OK on a day when I'd gotten a dose of the corn starch, I knew I wasn't sensitive to that dose.

But if I was sick on a day when I didn't get a dose of corn starch, it didn't tell me anything, because I could have been having an allergic reaction to something else, like mold in the air.

I found I felt OK on one day when I turned out to have consumed the vial with 5 mg of corn starch.

Before doing the blind trials, I'd been trying to desensitize myself by consuming 5 mg of corn starch per day, and I'd felt a slight reaction. But after I felt OK when I'd consumed 5 mg of corn starch blind, I knew the slight reaction I'd had was a nocebo effect. I was consuming the corn starch at the same time every day, and it seems I got used to feeling the reaction at that time of day.

So then I tried 10 mg of corn starch vs. placebo. I had to use arrowroot starch as the placebo, because I found I could see 10 mg in the water solution.

I felt OK on one day when I turned out to have consumed 10 mg of corn starch, so I knew 10 mg of corn starch doesn't noticeably affect me.

So then I tried 20 mg vs. placebo. I felt somewhat sick on the day I got the corn starch.

So I tried again with 25 mg. This time, I got rather sick when I ate the corn starch, for about a day; and I felt no worse than usual when I ate the arrowroot starch. This happened with my 4 vials, 3 times in a row - so there would be only a 1/64 chance of having that result by accident.

So it's definitely a real allergy, not just a nocebo effect. According to the USDA nutrients database, corn starch has 0.26% protein. So I'm sensitive to about 50 mcg of corn protein.

Knowing my actual sensitivity to corn protein has already been helpful to me. I avoided iodized salt for a long time, because it contains dextrose, which is made from corn in the USA. But I was able to calculate about how much corn protein I'd be getting per day from iodized salt, and it's far less than the amount I'm sensitive to. So I can use it as a source of iodine.