Happy 4th of July! This is a dangerous time for those with food intolerances and allergies. Things that I avoid like the plague at cookouts; ketchup, mustard, soy sauce and mayonaise. These contain corn syrup and distilled white vinegar. The soy sauce contains gluten. There are alternatives available. I use the gluten free version of the soy sauce and it tastes just the same. And I use Vegenaise for the mayonaise.
Also the biggest thing that I avoid is corn. Grilled corn is delicious, but not if it causes me to go into a flare.
Enjoy the holiday but be aware of what you eat.