Does being a vegetarian decrease or increase food allergies?

Depends: On individual person.Some still get allergy and some don't.

No impact: While not ingesting a food will generally keep your body from recognizing it's allergic or could become allergic (you could be allergic to sea urchin but you'd never know it), most studies have shown that avoiding foods doesn't delay or avoid food allergy very much if at all. We've gone back to introducing peanut butter and eggs, fish and shellfish to 9 mo olds.