Sulfites are a group of sulfur-based compounds that sometimes occur naturally and sometimes are added to foods primarily as preservatives. Sulfites, bisulfites, and metabisulfites are the dry chemical forms of the gas, sulfur dioxide. According to the Food Marketing Institute, the food industry uses six sulfiting agents. Any of these ingredients found on a nutrition label means the product contains sulfites:
- Sulfur dioxide
- Sodium sulfite
- Sodium bisulfite
- Potassium bisulfite
- Sodium metabisulfite
- Potassium metabisulfite
Where Sulfites are Found
Sulfur-based preservatives have been used for centuries to prevent browning on fruits and vegetables, to prevent black spots on seafood, to discourage bacterial growth in fermented beverages, and to condition bread dough.
In the 1980s the FDA began prohibiting the use of sulfites on fresh fruits and vegetables meant to be eaten raw (such as restaurant salad bars and supermarket produce), and they required companies to list all sulfiting agents used as preservatives in concentrations of at least 10 parts per million (ppm). Although sulfites are no longer added to most fresh foods, they still are found in many cooked and processed foods—and in some foods they occur naturally. Here is a partial list of foods that might contain sulfites:
- Bakery goods such as cookies, tortillas, waffles, pie/pizza crusts, breads containing dough conditioners
- Condiments such as horseradish, relish, pickles, olives, wine vinegar
- Fresh grapes (sulfites can be used on grapes as a fungicide)
- Dried and glacéed fruit , Maraschino cherries
- Bottled lemon and lime juice
- Jams and jellies
- Canned and frozen vegetables
- Vegetable juices
- Guacamole
- Molasses
- Shredded coconut
- Shrimp, scallops, lobster, crab, clams
- Soy protein products such as tofu
- Processed cheese foods
- Gravy
- Soup, noodle, and rice mixes
- Trail mix
- Potato and tortilla chips
- Dehydrated, pre-cut or peeled potatoes
- Beer, wine, wine coolers, cocktail mixes, hard cider
- Tea concentrates and instant tea
Sulfites in Wine
Because yeast produces sulfites during fermentation, sulfites are a natural by-product of the wine-making process. However, almost all winemakers add an additional small amount of sulfites to act as a preservative. Although the United States requires a sulfite warning label, all countries add sulfites to their wines; they simply aren’t required to list the fact on the label. Wine without added sulfites will last approximately 18 months.
What About Organic Wine?
According to the Organic Consumer’s Association, organic wine in the United States must be made without added sulfites. A wine labeled “organic” may still contain naturally-occurring sulfites; however, the sulfite level must be less than 20 ppm.
Do Sulfites Cause Headaches?
Many people believe the sulfites in wine, particularly red wine, cause headaches. Not true, states Andrew L. Waterhouse, internationally recognized wine chemist and Professor of Enology at University of California at Davis.
Dr. Waterhouse suggests that anyone believing sulfites cause headaches should eat a few orange-colored dried apricots, a 2-ounce serving of which contains approximately 112 mg sulfites. United States law stipulates that wines cannot contain more than 350 mg per liter sulfites, and that wines in excess of 10 mg per liter must have a warning label. White wines actually have slightly more sulfites than red wines. Apparently, something in red wines does cause headaches, but researchers don’t yet know what that is.
When to Avoid Sulfites
Sulfites are safe for most people. However, the FDA estimates that 1 out of 100 people are sensitive to sulfites and that approximately 5% of those with asthma are at risk of suffering an adverse reaction to sulfites. People can develop sulfite allergies at any point in life. While the most common symptom is breathing difficulty, reported allergic responses have also included chest tightness, dizziness, nausea, cramps, hives, and wheezing. In extreme (and fairly rare) cases, sulfites can cause anaphylactic shock.
For anyone with sulfite allergies it is important not to assume any food is safe. Diligently read all nutrition labels, including labels on bulk bins (ask to check the ingredient label on the original package, if necessary). In restaurants, ask the chef or server if sulfites are used in any food items—before, during or after preparation. When ordering potatoes, choose baked. Asthmatics should always carry an inhaler, and anyone who has had a reaction to sulfites should carry antihistamine.
