Sulfites Safe for Most, Dangerous for Some

by Food and Drug Administration (FDA)

It wasn't a special occasion — or even a fancy restaurant — but Karen, 37, will never forget that meal:

My boyfriend and I were at a hamburger joint, and I had a burger and fries. About 10 minutes after we finished eating, my throat began to itch. I grabbed my [asthma] inhaler but I could feel my throat constricting. I couldn't breathe and started to panic. When I passed out, my boyfriend flagged down a passing police car. The officer radioed for an ambulance, and I was rushed to the hospital. I was revived with a massive dose of epinephrine to counteract the reaction caused by the sulfite solution the potatoes had been soaked in before frying.

I know enough to stay away from wine, shrimp and other foods that contain sulfites, and take note whenever I don't feel right after eating something. But I never expected french fries to be sulfited. I've had allergic reactions to sulfites before, but this time I came close to dying.

I was angry that this happened to me. I felt powerless — I was careful and knowledgeable, and yet I couldn't protect myself. Who ever heard of a lethal french fry? Afterward, I refused to eat out in restaurants for almost two years, and I still can't visit people or go on vacation without knowing there is a hospital nearby.

The Food and Drug Administration estimates that one out of a hundred people is sulfite-sensitive, and that 5 percent of those who have asthma, like Karen (who asked that her last name not be used), are also at risk of suffering an adverse reaction to the substance. "By law, adverse reactions to drugs must be reported to FDA by doctors or pharmaceutical companies. But with sulfites and other food ingredients, reporting is voluntary so it's difficult to say just how many people may be at risk," cautions FDA consumer safety officer JoAnn Ziyad, Ph.D.

Complicating matters, scientists have not pinpointed the smallest concentration of sulfites needed to provoke a reaction in a sensitive or allergic person. FDA requires food manufacturers and processors to disclose the presence of sulfiting agents in concentrations of at least 10 parts per million, but the threshold may be even lower. The assay used to detect the level of sulfites in food is not sensitive enough to detect amounts less than 10 ppm in all foods (that's 1 part sulfite to 100,000 parts of food — the equivalent of a drop of water in a bathtub) so that's what the regulation has to be based on, explains Ziyad.

"The most rapid reactions occur when sulfites are sprayed onto foods or are present in a beverage, but the most severe reactions occur when sulfites are constituents of the food itself," says Ron Simon, M.D., head of Allergy, Asthma and Immunology at Scripps Clinic and Research Foundation in La Jolla, Calif.

A person can develop sulfite sensitivity at any point in life, and no one knows what triggers onset or the mechanism by which reactions occur. "Doctors believe that asthmatics develop difficulty breathing by inhaling sulfite fumes from treated foods," notes Dan Atkins, M.D., a pediatrician at the National Jewish Center for Immunology and Respiratory Medicine in Denver, Colo. He says that in a severe reaction an overwhelming degree of bronchial constriction occurs, causing breathing to stop. This can lead to lack of oxygen reaching the brain, heart, and other organs and tissues and, possibly, a fatal heart rhythm irregularity.

"We now know that asthmatics who have more severe symptoms and are dependent on corticosteroids, such as prednisone or methylprednisolone, are especially prone to sulfite sensitivity and are most at risk of having a severe reaction," notes Atkins. But it's a chicken-and-egg situation, notes Simon: "We don't know which comes first, the asthma or the sulfite sensitivity, because some people's first experience with asthma is a sulfite reaction, and as their asthma becomes more severe they eventually become steroid-dependent."

Sulfite sensitivity can be tricky to diagnose. Karen went to an internist and two pulmonary specialists without getting to the bottom of her problem.

"People who do experience adverse reactions to sulfites know that it's something they ate, but might not know what that something is," says Atkins. "I'll ask a patient complaining of an adverse reaction what he or she ate and drank when it occurred. If beer or wine doesn't seem to be the problem, I tend to dismiss sulfite sensitivity. But if I think sulfites may be the culprit, I'll do a challenge [a type of allergy test in which a small amount of the suspect substance is administered in a capsule or in a drink and the patient is monitored to see whether there is a reaction]."

If a person develops hives after ingesting sulfites, the doctor will do a prick test (a small concentration of sulfite is placed on the skin, which is then pricked; the test is positive if a welt develops on the spot). "People who have positive skin tests to sulfites are likely to be allergic to the additive, rather than have a sensitivity. These people, who are usually not asthmatic, are most at risk of anaphylactic shock, [a life-threatening reaction]," says Simon.

Regulatory Status in Flux

Sulfur-based preservatives, or sulfites, have been used around the world for centuries to:

• inhibit oxidation ("browning") of light-colored fruits and vegetables, such as dried apples and dehydrated potatoes
• prevent melanosis ("black spot") on shrimp and lobster
• discourage bacterial growth as wine ferments
• "condition" dough
• bleach food starches
• maintain the stability and potency of some medications.

When the Federal Food, Drug, and Cosmetic Act was amended in 1958 to regulate preservatives and other food additives, FDA considered sulfites to be generally recognized as safe (GRAS). But when FDA reevaluated their safety and proposed to affirm the GRAS status of sulfiting agents in 1982, the agency received numerous reports from consumers and the medical community regarding adverse health reactions. In response, FDA contracted with the Federation of American Societies for Experimental Biology (FASEB) to examine the link between sulfites and reported health problems that ranged from chest tightness or difficulty breathing to hives to fatal anaphylactic shock.

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