Sulfites are sulfur based preservatives that are used to prevent or reduce discoloration of light-colored fruits and vegetables.
by POPSUGAR Fitness
Sulfites are sulfur based preservatives that are used to prevent or reduce discoloration of light-colored fruits and vegetables. They are also used to prevent black spots on shrimp and lobster. They are used to condition dough and maintain the stability and potency of certain medications.
Most (except for a few) wines contain sulfites. Yeast naturally produces sulfites during fermentation and most winemakers add sulfites to inhibit the growth of microorganisms. All wines made in the U.S. require a "sulfite" warning label. There are no such rules for wines made in other countries.
Why am I telling you all this? Because according to the FDA, 1 out of every 100 people has a sensitivity to sulfites. They lack the natural enzyme to break them down. Symptoms include difficulty breathing, chest tightness, nausea, hives or anaphylactic shock.
Sulfites can occur naturally in foods like wine and are added to certain foods as well. 
Some common foods that contain sulfites are baked goods, soup mixes, jams, pickled foods, bottled lemon and lime juice, maraschino cherries, and dried fruit.
Look at the ingredients and you may see:
sulfur dioxide
sodium sulfite
sodium bisulfite
potassium bisulfite
sodium metabisulfite
potassium metabisulfite
These are all sulfites, so if you are experiencing any of these symptoms, you may try avoiding sulfites to see if your symptoms go away. Or you can try sulfite free food and wine.
A lot of us are trying our best to eat as healthy as possible, but sometimes it's hard because there are so many factors to consider. One simple tip on how to determine how healthy a food really is for you is to check out its shelf life. The longer it lasts on the shelf, chances are the worse it is for you. Think about it: organic fruits and veggies hardly make it home before going bad but a loaf of white Wonder Bread can sit in your pantry for a month without the first trace of mold. 