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 1970's and
1980's. 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.