Sulfites: you may have seen them on the ingredient list of your beloved dried mango slices or favorite salami. Or perhaps you've heard sulfites are responsible for your red wine-induced headaches. 

But what are sulfites?

hot dog, mustard, sausage, ketchup, bun, meat, sandwich, relish, beef, bread, cheese
Kevin Del Orbe

Sulfites are inorganic salt compounds that occur naturally in the human body and some foods. They are also added as preservative to other foods and many medications.

While most people have no issue with sulfites, a small percentage (an estimated 1% of people, and up to 5% of people who have asthma) of the population experience adverse effects after consuming them.

Where are they found?

nut, almond, peanut
Christin Urso

Sulfites are naturally found in peanuts, vinegar, eggs, kale, broccoli, teas, molasses, onions, strawberries, blackberries, plums, coconut, and rapeseed oil (found in canola oil). 

They can also be a natural bi-product of fermentation, which is why they're found in beers, ciders and wines, and other foods like pickles, horseradish paste, and olives.

wine, white wine, toast, red wine, champagne, alcohol
Kristine Mahan

And although red wine is high in sulfites compounds, white wines and sweet wines actually tend to have more sulfites than red.

Sulfites are also commonly added as a preservative (often under the name "sodium bisulfite, "potassium bisulfite," "sodium metabisulfite” or "sulphites") to dried fruits, packaged snacks and baked goods.

They're also found in pre-cut and peeled potato products, canned fruits and vegetables, some jams and jellies, refrigerated doughs, and preserved seafood and meats (like hot dogs).

Are they safe?

toast, bread, egg, sweet, butter, cake, pastry, cream
Caty Schnack

The FDA currently has them on their "GRAS" list (meaning they give them a thumbs up for safety).

But they do acknowledge they may cause reactions in some people, and require foods with more than 10 sulfite parts-per-million to have a "CONTAINS SULFITES" label to alert consumers. 

onion, garlic, vegetable, shallot, condiment
Jocelyn Hsu

And, the FDA has banned their addition to fresh fruits and vegetables, which was once a common practice to preserve freshness and prevent browning. They also don't allow them to be added to foods with thiamin, as sulfites can destroy this B vitamin.

The USDA also does not allow it's addition to fresh meats, because it can make meat look fresher than it really is, which can lead to safety issues. 

How do you know if you're sensitive to them?

vegetable, sweet
Christin Urso

Sensitivity may develop at any time in a person's life, and common symptoms include nausea, diarrhea, abdominal pains, low blood pressure, skin rashes and hives, and in rare severe cases, anaphylaxis.

These symptoms are much more common in people who have allergies and asthma. 

And as far as the infamous "wine headache" goes, scientific data has never been able to prove sulfites are what causes wine headaches, and many point out that dried fruit contains about five times as many sulfites per serving compared to wine, and few people report headaches after their consumption.

What can I do to avoid them?

beer, juice, cider, sweet, ice, tea
Spoon University

If you are sensitive to sulfites or simply wish to avoid them, look for the warning label and select products without it.

Some brands (like Trader Joe's) offer sulfite-free versions of dried fruit and other products that often contain them, and many other brands do the same. Read labels, and purchase wisely.

You can also limit your intake of foods that naturally contain sulfites, including wine, beer, and eggs.