The Asthma Center

Should I avoid sulfites and/or other preservatives?

Should you avoid sulfites and/or other preservatives?

Additives are chemicals purposely added to foods such as flavor enhancers, preservatives, sweeteners, food colorings, stabilizers and antioxidants. Additives and inadvertent contaminants (like pesticides and toxic man-made chemicals) introduce chemicals into the diet. Both additives and contaminants may have medical repercussions after ingestion either immediately or over an extended period. If you suspect a food-related exacerbation of asthma, oral food challenges, special food skin testing and/or oral additive or contaminant challenges may be performed.

The most common additives reported as a problem in conjunction with asthma are sulfites (sodium and potassium bisulfite, sodium and potassium metabisulfite, sodium sulfite and sulfur dioxide). In order to make food appear fresh and retain its natural color, many restaurants used to spray foods with sodium metabisulfite. Although it is now against federal law to spray metabisulfite on restaurant food, this activity may still be practiced in some locations. Ingesting a certain quantity of these sulfites may cause a sudden and severe episode of asthma if you are sensitive.

Sulfites may still be sprayed on foods such as lettuce, salad greens, bananas, avocados, mayonnaise based foods and shrimp in restaurants. Sulfites are also found as ingredients in certain foods such as potato based foods (french fries, potato chips) and in certain wines. They prevent many foods from turning brown as they oxidize. Sensitivity to metabisulfites can be identified by performing challenges under controlled conditions. If you are sensitive to metabisulfite, you should read all content labels of processed food. Certain medications may also contain sulfites. You need to question the preservative basis of all prescription and over-the-counter medications.

Under rare circumstances, other food additives can worsen asthma. These additives include monosodium glutamate (MSG), sodium benzoate, sodium nitrate, saccharin, aspartame (NutraSweet®) and tartrazine (FD&C dye #5). Special challenge procedures can be performed to establish sensitivity to these food additives.