Sulfites are a group of similar chemicals that are commonly used as a food enhancer and preservative to maintain food color and prolong shelf-life, prevent the growth of micro-organisms, and to maintain the potency of certain medications. They may come in various forms, such as:
- Sulfur dioxide
- Potassium bisulfite or potassium metabisulfite
- Sodium bisulfite, sodium metabisulfite or sodium sulfite
The use of sulfites as preservatives in foods and beverages increased dramatically in the 1970’s and 1980’s. After several cases of severe reactions to sulfites were reports, a ban by the FDA went into effect in August, 1986. This ban prohibited use of sulfites in fresh fruits and vegetables. Although reactions to sulfites were recognized initially with salad bars in restaurants, this is no longer a common source for sulfite exposure. Sulfites continue to be used in potatoes, shrimp, and beer/wine, and are also used in the pharmaceutical industry. Although shrimp are sometimes treated with sulfites on fishing vessels, the chemical may not appear on the label. A list of foods associated with sulfites can be found below.
Sulfites occur naturally in all wines to some extent and are commonly introduced to arrest fermentation at a desired time, and may also be added to wine as preservatives to prevent spoilage and oxidation at several stages of the winemaking. In general, sweet (dessert) wines contain more sulfites than dry wines, and white wines contain more sulfites than red wines. In the United States, wines bottled after mid-1987 must have a label stating that they contain sulfites if they contain more than 10 parts per million.
Labeling regulations don’t require that products indicate the presence of sulfites in foods other than wine; however, many companies voluntarily label sulfite-containing foods. Regulations do exist that require that ingredients lists show sulfites if they were added to a product, but this requirement applies only if they were intentionally added in formulation and not if they are contained in an ingredient. If a product includes an ingredient that contains sulfites, such as dried fruit, then the ingredients label will list only “dried fruit” and is not required to indicate whether the dried fruit itself contains sulfites. Furthermore, the products most likely to contain less than 10 ppm (fruits and alcoholic beverages) do not require ingredients labels, so the presence of sulfites is usually undisclosed.
Most beers no longer contain sulfites. Sulfites are added to many medications, including some of the medications given to treat asthma and allergic reactions.
Although a reaction to sulfite is not a true allergy, individuals who are sensitive to it may experience a variety of symptoms including asthma, diarrhea, abdominal pain and cramping, nausea and vomiting, hives, itching, localized swelling, difficulty in swallowing, faintness, headache, chest pain, loss of consciousness, “change in body temperature,” “change in heart rate,” and non-specific rashes. For normal individuals, exposure to sulfite appears to pose little risk. Sulfite-sensitive asthmatics, however, are at risk of having a severe asthma attack when exposed to sulfites.
To date there is no specific diagnostic test, other than a food challenge, available to determine if someone has a true sulfite sensitivity. A double-blinded, placebo-controlled, food challenge in which neither the doctor of the patient knows knows whether a food containing sulfites or a placebo is given while symptoms are monitored is required to confirm a case of suspected sulfite sensitivity.
Foods Frequently Containing Sulfites
- Alcoholic/non-alcoholic beer, cider, wine
- Baked goods, e.g., breads, cookies, pastries, waffles
- Bottled lemon and lime juice/concentrate
- Canned/frozen fruits and vegetables, e.g., mushrooms, sliced apples, olives, peas, peppers, pickles, pickled onions, tomatoes
- Cereal, cornmeal, cornstarch, crackers, muesli
- Condiments, e.g., coleslaw, horseradish, ketchup, mustard, pickles, relish, sauerkraut
- Deli meat, hot dogs, sausages
- Dressings, gravies, guacamole, sauces, soups, soup mixes
- Dried fruits/vegetables, e.g., apples, apricots, coconut, mincemeat, papaya, peaches, pears, pineapple, raisins, sun dried tomatoes
- Dried herbs, spices, tea
- Fish, including crustaceans and shellfish, e.g., shrimp (fresh/frozen)
- Fresh grapes, lettuce
- Fruit filling, fruit syrup, gelatin, jams, jellies, marmalade, molasses, pectin
- Fruit/vegetable juices, e.g., coconut, grape, sparkling grape, white grape
- Glazed/glacéed fruits, e.g., apples, grapes, maraschino cherries
- Potatoes, e.g., frozen french fries, dehydrated, mashed, peeled, pre-cut
- Snack foods, e.g., candy, chocolate/fruit bars, tortilla/potato chips, soft drinks, trail mix
- Soy products
- Starches, e.g., corn, potato, sugar beet; noodles, rice mixes
- Sugar syrups, e.g., glucose, glucose solids, syrup dextrose
- Tomato paste/pulp/puree
- Vinegar, wine vinegar