I was running some common things I would say through my head, and realize I seldom use the word foods.
For instance, in Robert's sentence, I would say "There are 100 different TYPES of food in this store"
I don't think I say foodstuffs, but rather, types of foodstuff, or all this foodstuff.
I honestly can't say if this is a personal preference, or if it's a difference between the way we speak english.
I'd like to get some other people views too.
btw, I always find it odd when a Brit says "maths", I'm sure it sounds just as off to you when a Yank says "math"