Sulfites are counted among the top nine food allergens, but a reaction to sulfite is not a true allergy.[9] Some people (but not many) have positive skin allergy tests to sulfites indicating true (IgE-mediated) allergy.[10] It may cause breathing difficulty within minutes after eating a food containing it,[11] asthmatics[12][13] and possibly people with salicylate sensitivity (or aspirin sensitivity)[14][15] are at an elevated risk for reaction to sulfites. Anaphylaxis and life threatening reactions are rare.[10] Other symptoms include sneezing, swelling of the throat, and hives.[15]
In the U.S., labeling regulations do not require products to indicate the presence of sulfites in foods unless it is added specifically as a preservative;[8] however, many companies voluntarily label sulfite-containing foods. Sulfites used in food processing, but not specifically added as a preservative, are only required to be listed if there are more than 10 parts per million (ppm) in the finished product.
The products most likely to contain sulfites (fruits and alcoholic beverages less than 10ppm) do not require ingredients labels, so the presence of sulfites usually is undisclosed.
In 1986, the U.S. Food and Drug Administration banned the use of sulfites as preservatives on foods intended to be eaten fresh (such as salad ingredients).[8] This has contributed to the increased use of erythorbic acid and its salts as preservatives.[16]
In Australia and New Zealand, sulfites must be declared in the statement of ingredients when present in packaged foods in concentrations of 10 mg/kg (ppm) or more as an ingredient; or as an ingredient of a compound ingredient; or as a food additive or component of a food additive; or as a processing aid or component of a processing aid.[17]
Sulfites are widely used to extend the shelf life of products. Because it is often difficult to know whether a food contains sulfites, people may not realize they have a sensitivity to sulfites when they are having reactions to food or drinks. Sulfites are also known to destroy vitamin B1 (thiamin),[18] a vitamin essential for metabolism of carbohydrates and alcohol.
