Intolerance to food additives might also be responsible for stuffy nose. 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.