Sue and Tharini were the ones who drew attention to this. I wished to contribute in time of the food allergy awareness month. I am no expert but I list down here some of the allergies I have come across.
I had not come across food allergies much, expect in the novels which talked of peanut allergy and even death through that.
My mother is allergic only to panner which causes her face to break into small pimple like eruptions and my chithi ( aunt) is allergic to yam which causes in her a similar reaction.
Sometimes colacasia( arbi/ chaypankezhangu) can cause severe itchiness in the throat. But that is a matter of luck. There is no way to tell as far as I know till you begin eating it. And it is only a mild irritation. Not life threatening or any such.
Since I moved to Chennai post marriage, I have encountered a few more food allergies.
I know that asthmatics avoid cucumber/ snake gourd/ bananas during periods of wheezing. My MIL is one such.
Navy's cousin has milk intolerance to such an extent that she has to avoid not just milk but anything with even traces milk - so she has never had chocolate, cake, curd, milk, bread, butter, cheese, pizza, naan, white gravies, etc. This causes a lot of anxiety among us when we go out to eat because even a roti dough may have some milk or a seemingly tomato gravy may have cream in it. There have been occasions when she was nearly choked due to the restaurant not taking our request seriously enough.
It is only when I saw her that I realized how distressing and disruptive an allergy could be.