Sulfur-based preservatives -- sulfites -- have been used for centuries to inhibit the oxidation of light-colored fruits and vegetables (the "browning" of apples or potatoes), prevent melanosis on shrimp and lobster, block bacterial growth in fermenting wine, condition dough, bleach food starches, and maintain the stability and potency of certain medications (see side bar). Unfortunately, many people, including approximately 5% of asthmatics, are allergic or sensitive to sulfites. According to a report in the FDA Consumer, the FDA currently prohibits the use of sulfites for maintaining the color and crispness of fruits and vegetables meant to be eaten raw; it also requires manufacturers to label products (including packaged, bottled, and bulk foods) that contain sulfiting agents. However, current FDA regulations do not apply to restaurants.
Sulfites in a concentration lower than 10 parts per million can trigger an attack. The most rapid reactions occur when sulfites are sprayed on food or are used in a beverage, but the most severe reactions occur when sulfites are in the food itself. Asthmatics are probably sensitive, not allergic, to sulfites; exposure occurs when sulfite fumes are inhaled from treated foods. Bronchoconstriction can be severe enough to completely block breathing, causing hypoxemia with brain damage, heart or other organ damage, or fatal arrhythmia. Patients with asthma who are dependent on oral corticosteroids are more apt to be sulfite sensitive, and they have an increased risk of severe reactions. However, in some cases, the very first asthma attack is a sulfite reaction.
Sulfite sensitivity can be difficult to diagnose. A sulfite challenge may be appropriate for patients who react adversely to certain foods. For example, if the suspect food causes hives, a sulfite skin-prick test may be performed. Patients with a positive skin test are more likely to be allergic, rather than sensitive, to the sulfite; they usually are not asthmatic and are at greater risk for anaphylaxis. According to the FDA Consumer, people who have had a serious sulfite reaction should carry an antihistamine and a self-injectable epinephrine when they eat out, and asthmatics should use a bronchodilator. Sulfite-sensitive people should also read food labels, ask store managers or waiters to check labels on bulk foods, avoid foods known to contain sulfites in other forms-and never just assume a food is safe to eat.
source:Medical Sciences Bulletin
Sulfites in a concentration lower than 10 parts per million can trigger an attack. The most rapid reactions occur when sulfites are sprayed on food or are used in a beverage, but the most severe reactions occur when sulfites are in the food itself. Asthmatics are probably sensitive, not allergic, to sulfites; exposure occurs when sulfite fumes are inhaled from treated foods. Bronchoconstriction can be severe enough to completely block breathing, causing hypoxemia with brain damage, heart or other organ damage, or fatal arrhythmia. Patients with asthma who are dependent on oral corticosteroids are more apt to be sulfite sensitive, and they have an increased risk of severe reactions. However, in some cases, the very first asthma attack is a sulfite reaction.
Sulfite sensitivity can be difficult to diagnose. A sulfite challenge may be appropriate for patients who react adversely to certain foods. For example, if the suspect food causes hives, a sulfite skin-prick test may be performed. Patients with a positive skin test are more likely to be allergic, rather than sensitive, to the sulfite; they usually are not asthmatic and are at greater risk for anaphylaxis. According to the FDA Consumer, people who have had a serious sulfite reaction should carry an antihistamine and a self-injectable epinephrine when they eat out, and asthmatics should use a bronchodilator. Sulfite-sensitive people should also read food labels, ask store managers or waiters to check labels on bulk foods, avoid foods known to contain sulfites in other forms-and never just assume a food is safe to eat.
source:Medical Sciences Bulletin
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