What are sulfites and what are they used for?

Sulfites are chemicals used as preservatives to prevent browning and discoloration in foods and beverages during preparation, storage, and distribution.

Sulfites are found in certain foods and beverages, and in a variety of medications. The use of sulfites as preservatives in foods and beverages increased dramatically in the 1970s and 1980s. Because of cases of severe reactions to sulfites, a ban by the FDA went into effect in August 1986 to prohibit the use of sulfites in fresh fruits and vegetables. Sulfites have been used in wine-making for centuries.

Although reactions to sulfites were recognized initially with salad bars in restaurants, this has not been a source for sulfite exposure for more than two decades. Sulfites continue to be used in potatoes, shrimp, beer and wine, and are also used in the pharmaceutical industry. Sulfites are added to many medications, including some of the medications given to treat asthma and allergic reactions.

How do I determine if a food product contains sulfites?

Look on food labels for any of the following sulfite-containing ingredients:

  • Sulfur dioxide
  • Potassium bisulfite
  • Potassium metabisulfite
  • Sodium bisulfite
  • Sodium metabisulfite
  • Sodium sulfite

What types of health problems may arise from sensitivity to sulfites?

Sulfites have been implicated as a cause of asthma symptoms that may range from mild wheezing to potentially life-threatening asthmatic reactions. It is also a rare cause of anaphylaxis (generalized allergic reaction) in people who have become allergic to sulfites.

Estimates of the number of people who have sulfite-sensitive asthma vary. People with sulfite-sensitive asthma develop asthma symptoms by eating and drinking foods and beverages that contain sulfites. Most reactions occur from inhaling sulfur dioxide that is generated from sulfite-containing food or beverage items.

How is sulfite sensitivity diagnosed?

Your doctor may suspect that you are sensitive to sulfites based on your medical history and aspects of your asthma. The diagnosis of sulfite sensitivity can be confirmed by a "challenge."

The challenge is done in a step-by-step fashion, and small doses of sulfite are used, so the asthma reaction that occurs in this challenge is usually mild. In most cases, the initial solution dose is too small for the sulfite-sensitive person to react to, so increasing doses are given, waiting 20-30 minutes between steps. Once a reaction takes place, it is measured — by lung function studies (or "spirometry") — and can be quickly reversed with an inhaled bronchodilator medication. The entire challenge procedure takes less than 2 to 2-1/2 hours.

If you are asthmatic, your chances of being sensitive to sulfites are between 1 in 20 and 1 in 100. If you suspect you may be sensitive to sulfites, you should be seen by a board-certified allergy/immunology physician. If you are not asthmatic, sulfite sensitivity would be very unusual. before beginning a lifelong avoidance of sulfited foods and beverages.

How is sulfite sensitivity treated?

The best treatment of sulfite sensitivity is a lifelong avoidance of sulfite-containing foods and beverages.

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