Sulfites are commonly used in the processing and storage of various foods and drinks. In the U.S., they were finally banned for use on produce in 1986. At that time the FDA also required other beverages containing sulfites, such as wine, beer and dried fruit to have warning labels.
Sulfites are sulfur-based preservatives that are used to prevent or reduce discoloration of light-colored fruits and vegetables, prevent black spots on shrimp and lobster, inhibit the growth of microorganisms in fermented foods such as wine, condition dough, and maintain the stability and potency of certain medications. Sulfites can also be used to bleach food starches, to prevent rust and scale in boiler water that is used to steam food and even in the production of cellophane for food packaging.
These potentially toxic and harmful substances can cause nausea
and precipitate asthma
attacks in sensitive individuals. The "salad bar" syndrome is caused by sulfite sprays used on vegetables to keep them "fresh" longer.
A person can develop sulfite sensitivity
at any point in life.Products That Contain Sulfites
Sulfites can occur naturally in foods or are added to enhance food products. Sulfites are produced naturally during the fermentation of wine. There is a variety of foods that contain sulfites including baked goods, soup mixes, jams, canned vegetables, pickled foods, gravies, dried fruit, potato chips, trail mix, beer, wine, vegetable juices, bottled lemon juice, bottled lime juice, tea, condiments, molasses, fresh or frozen shrimp, guacamole, maraschino cherries, and dehydrated, pre-cut, or peeled potatoes.
There are six names used for sulfites: sulfur dioxide, sodium
sulfite, sodium bisulfite, potassium
bisulfite, sodium metabisulfite, and potassium metabisulfite. Sulfites, bisulfites and metabisulfites are all dry chemical forms of the gas, sulfur dioxide.
Foods that may contain sulfites (partial list):
- Alcoholic Beverages (labeling of sulfites in alcoholic beverages is required if the concentration is 10 parts per million or greater.)
- Bakery Items: Breads containing dough conditioners, cookies, crackers, pie and pizza crusts, tortillas, waffles.
- Beverages: Beverages containing sugar or corn syrup, dried citrus fruit beverages, canned bottled, and frozen fruit juices.
- Condiments: Horseradish, relishes, pickles, olives, wine vinegar.
- Dairy: Processed cheese foods.
- Dried Foods: Dried herbs and spices, dried fruits, trail mixes.
- Fish and Shellfish: Fresh shrimp and scallops frozen, canned or dried clams, shrimp, lobster, crab, scallops, dried cod.
- Fruits: Fresh grapes, dried fruits (including raisins and prunes and especially pale fruits that have not discolored), canned, bottled and frozen fruit and juices, maraschino cherries, glazed fruit.
- Gelatins, Fillings, Frostings: Fruit fillings, flavored and unflavored gelatin, pectin, jelling agents, canned frostings and frosting mixes.
- Grain Products: Cornstarch, modified food starch, spinach pasta, gravies, hominy, breading, batters, noodle and rice mixes.
- Hard Candies
- Jams and Jellies
- Nuts: Shredded coconut.
- Plant Protein Products: Soy protein products including tofu, textured vegetable protein, infant formula.
- Snack Foods: Filled crackers, dried fruit snacks, trail mixes, tortilla chips, potato chips.
- Sugars: Brown, white, powdered and raw sugars.
- Vegetables: Vegetable juices, canned vegetables (including potatoes), pickled vegetables (including cauliflower, peppers, sauerkraut), "fresh cut" potatoes (as delivered to restaurants), frozen vegetables (including french fries and deli potato salad).
Incidence; Causes and Development
The FDA estimates that 1% of people are sulfite-sensitive and 5% of those also suffer from asthma
It appears that sulfite sensitivity
may be caused by a relative deficiency of the enzyme sulfite oxidase
which breaks down sulfites and requires molybdenum
as a cofactor
. As with lactase
deficiency, this is a metabolic problem and not an allergic one.
Signs and SymptomsAsthma
, nasal and sinus
, postnasal drip, frontal headache and bronchospasm
can be triggered by sulfites.
Diagnosis and Tests
Sulfites can be measured in the urine, and used as a means of monitoring symptom correlation with treatments such as molybdenum