Sulfites are chemicals used as preservatives to inhibit browning and discoloration in foods and beverages during preparation, storage, and distribution. Sulfites have been used in wine making for centuries.
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. Due to cases of severe reactions to sulfites, 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. Sulfites are added to many medications, including some of the medications given to treat asthma and allergic reactions.
Sulfite containing ingredients to look for on food labels include:
- Sulfur dioxide
- Potassium bisulfite
- Potassium metabisulfite
- Sodium bisulfite
- Sodium metabisulfite
- Sodium sulfite
Sulfites have been implicated as a cause of asthma symptoms that may range from mild wheezing to potentially life-threatening asthmatic reaction. It is also a rare cause of anaphylaxis (generalized allergic reaction) in people who have become allergic to sulfites.
People with sulfite-sensitive asthma experience asthma symptoms with consumption of foods and beverages that contain sulfites. Estimates regarding the prevalence of sulfite sensitive asthma vary. Most reactions occur due to via inhalation of sulfur dioxide generated from sulfite containing food or beverage items during the process of eating.
Your doctor may suspect sensitivity to sulfites based on your medical history and aspects of your asthma. The diagnosis of sulfite sensitivity can be confirmed by a "challenge" in which sulfite is administered in solutions or capsules of increasing concentration.
As with other substances (allergens, irritants, etc.) that an asthmatic is sensitive to, the best treatment for sulfite sensitivity is avoidance. However, before recommending a program of sulfite avoidance, it is usually important to confirm presence of sulfite sensitivity by carrying out a challenge procedure.
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, so increasing doses are administered, waiting 20-30 minutes between steps. Once a reaction takes place, it is measured — by lung function studies (or "spirometry") — and can be promptly reversed with an inhaled bronchodilator medication. The entire challenge procedure takes less than 2- 2 1/2 hours.
If you are not asthmatic, sulfite sensitivity would be very unusual. If you are asthmatic, your chances of being sensitive to sulfites is in the range of between 1 in 10, and 1 in 20. If you suspect you may be sensitive to sulfites, you merit evaluation with a board-certified Allergy/Immunology physician before embarking on a program of lifelong avoidance of sulfited foods and beverages.