Food additives may trigger stuffy noses in some

March 24, 2003

NEW YORK (Reuters Health) - For some people plagued by a chronically stuffy nose, intolerance to food additives might be to blame, a new study suggests.

Italian researchers found that of 226 people with persistent nasal congestion not caused by allergies, 20 had reactions to monosodium benzoate, a preservative widely used in processed foods. When these men and women followed an additive-free diet, their nasal woes waned, according to findings published in the journal Allergy.

Patients in the study had what is known as non-allergic rhinitis. The symptoms, including chronic nasal congestion, runny nose and sneezing, are similar to those of hay fever, but the condition does not involve the abnormal immune response that triggers allergy symptoms. People with non-allergic rhinitis may develop symptoms in reaction to things like temperature changes, cigarette smoke or strong odors.

None of study patients tested positive for allergies to food or to common allergic rhinitis triggers such as pollen, mold and pet dander. But a small percentage appeared to have intolerance to monosodium benzoate--a reaction that differs from immune system-driven allergies.

The findings, say the study authors, suggest that in at least some cases in which the cause of patients' rhinitis is unknown, intolerance to food additives might be at work.

Dr. Maria Luisa Pacor of the University of Verona and her colleagues came to this conclusion after having 226 teenagers and adults with non-allergic rhinitis follow "additive-free" and "additive-rich" diets.

After one month on the additive-free diet, 20 patients, or about nine percent, showed an improvement in their rhinitis, and in six of these patients the symptoms disappeared. But after a few days on a diet heavy in processed foods containing preservatives, dyes and other additives, their symptoms resurfaced.

To pinpoint the culprit, Pacor's team conducted a double-blind placebo-controlled challenge. In this procedure, patients are given capsules containing either a specific food additive or an inactive substance in random order; neither the doctors nor the patients know what is inside each capsule.

The researchers found that all 20 of the patients who improved on the additive-free diet developed runny, stuffy noses and sneezing within a few hours of being given monosodium benzoate.

"This is the first controlled clinical trial that demonstrates the possible role of food additives in persistent rhinitis," Pacor and her colleagues write.

Still, the researchers point out that only six of the 20 patients with intolerance to monosodium benzoate saw a complete remission of their symptoms on the additive-free diet. This, they note, suggests that for some people, food additives may aggravate chronic rhinitis, but not be the underlying cause.

SOURCE: Allergy, February 2004.