You would be unlucky to be so sensitive to corn that the oil would affect you, what else was in the stew? any grains of any kind? lentils?. Very doubtful oil was the problem imho.
For me, that is not the case. Anything at all derived from corn seems to be a real problem for me.
I have been low level sick (not really low level) for a couple of years now, and it seems to be because of the minute quantities of corn-derived products in foods and in medications, both over the counter and prescription.
Sadly, I think you can be having what seems to be a low-level reaction to something, but if you keep having it over the long run it can really adversely impact your health.
When I say low level, I mean the reaction that is like a gluten reaction is a smallish one. But at the same time I have been suffering with many vitamin deficiency symptoms which are quite horrible -- twitching, quivering, trembling, teeth chattering -- and this all feels like terrible anxiety. I jump a couple of inches when I hear sudden sounds, but not bad sounds like little beeps when you play a computer game, I jump right off of the bed. And I get lots of cramps, leg cramps, foot cramps, all over cramps. I have even had symptoms of potassium deficiency -- sudden, overall weakness, feeling like a great big overcooked noodle, thinking I was going to just drop to the floor. Sometimes I can't sleep at all, and I think that might be caused my lack of magnesium.
All these deficiency symptoms can be inter-related. Apparently, without sufficient magnesium, you can't hold on to enough potassium. And you need more B-6 with the magneisum. I take tons of supplements, and they help, but only a little tiny bit. And of course it is very difficult to FIND supplements with no corn-derived ingredients.
I recently gave up my blood pressure medication, which apparently has corn things in it, and finally got better. I had already given up the other meds that I knew had corn in them (almost all do, by the way). I now use a patch for blood pressure. The only non-steroidal anti-inflammatory I can find is Aleve and I'm not sure about it. Now I read all malic acid (which I need for CFS) is made from corn. Don't know if that's true, but I'm trying to find out.
You're really between the rock and a hard place if you have vitamin deficiencies and need supplements and at the same time those supplements are full of ingredients that caused the deficiencies in the first place!
As I said, I don't go anywhere near corn oil. I avoid citric acid, maltodextrin, dextrose, glucose, cellulose -- the whole long list, actually. Xanthan gum is also a problem for me, and I think it is because it is usually made from corn. At home I use xanthan gum from Authentic Foods that isn't made from corn, and it seems not to bother me. I am sad I am now going to have to give up Joan's gluten free bread, as it is just about the only one I like. It has xanthan gum in it. I have written them and begged them to give up corn, but of course they believe only a few people have a problem with it.
I apologize for being so long-winded, but this corn thing is running and ruining my life, my health, my ability to participate in any meaningful way in any activity.... I only hope we can somehow get corn labeled, and maybe eventually then important pharmaceutical ingredients might be made from other starches or other plants. And this is while I am trying like the devil to avoid it! Citric acid is in so many things! And maltodextrin. Sometimes that is made from tapioca, but it is usually labeled when it is. Not so for corn, though.
I recently discovered kosher-for-passover ingredients. That can mean completely grain-free, apparently. At the right time of year there are noodles and matzo that are wheat and corn-free. There is even a kosher-for-passover baking powder out there somewhere that is corn-free. The only other one I can find is Feather- something.
For me, and I am guessing more than a few other people, corn is a very big deal.