Monosodium benzoate hypersensitivity in subjects with persistent rhinitis

BACKGROUND: Very few data are available from the literature on whether nonatopic subjects affected by persistent rhinitis may show the appearance of objective symptoms of rhinitis after the ingestion of food additives such as tartrazine (E102), erythrosine (E127), monosodium benzoate (E211), p-hydroxybenzoate (E218), sodium metabisulphite (E223), and monosodium glutamate (E620). It is still unclear whether the ingestion of food additive may cause, as well, a consensual reduction of nasal peak inspiratory flow (NPIFR). Therefore, we used a double-blind placebo-controlled (DBPC) study to evaluate this hypothesis. PATIENTS AND METHODS: Two hundred and twenty-six consecutive patients (76 males and 150 females) aged 12-60 years (mean age 40.2 +/- 16.3 years). After 1 month of an additive-free diet regimen, an open challenge was carried out (food additive-rich diet for 2 weeks). After this period, challenges were administered in a DBPC manner using the above-mentioned substances under investigation. RESULTS: Twenty of 226 subjects (8.8%) reported an improvement of the symptoms of rhinitis after additive-free diet. More precisely, six of 226 (2.6%) were symptom-free and 14 of 226 (6.2%) showed an improvement in their symptoms after an additive-free diet. As far as the results for DBPC are concerned, 20 challenges with monosodium benzoate induced both objective (i.e. sneezing and rhinorrhoea) and subjective symptoms (nasal blockage and nasal itching) of rhinitis with reduction of NPIFR >/=20%, 45 challenges induced subjective symptoms of rhinitis (i.e. nasal blockage and nasal itching), without reduction of NPIFR >/=20% of the basal value, two with tartrazine, seven with erythrosine, 19 with monosodium benzoate, three with p-hydroxybenzoate, six with sodium metabisulphite, and eight with monosodium glutamate, respectively. CONCLUSIONS: The observation that nonatopic persistent rhinitis may be caused by the frequent, probably daily, ingestion of small doses of a nontolerated substance is intriguing and suggests that at least some patients with 'chronic vasomotor rhinitis' may be intolerant to a particular food additive. Therefore, food additives can be considered triggers or aggravating factors, rather than aetiological factors.