Background: The incidence of allergic symptoms to cedar pollen has reached epidemic proportions in Japan. Intravenous injection of beta-1,3-glucan in human subjects is known to induce a T(H)1 response, whereas oral uptake does not.
Objective: It was examined whether orally ingested, superfine dispersed beta-1,3-glucan (SDG), easily absorbed by intestinal mucosa, would alleviate allergic symptoms.
Methods: Allergic patients were orally administrated either SDG (n = 30) or nondispersed beta-1,3-glucan (n = 30), and allergic symptoms were assessed clinically in a double-blind, placebo-controlled randomized study.
Results: SDG alleviated ongoing symptoms of Japanese cedar pollen-induced rhinorrhea, sneezing, nasal congestion, and itchy watery eyes, and its oral uptake before symptom onset exhibited preventive effects. Alleviation of allergic symptoms was evident not only for seasonal allergy to cedar pollen but also for perennial allergy. Oral ingestion of beta-1,3-glucan in individuals with allergic tropism could reduce the spontaneous increase in both allergen-specific and total IgE titers. The clinical responses to treatment were well correlated with the capacity of monocytes to bind to beta-1,3-glucan. Although SDG reduced allergic symptoms, the oral uptake of nondispersed beta-1,3-glucan produced no clinical effects, despite the identical amount of beta-1,3-glucan in both preparations.
Conclusion: We postulate that orally taken beta-1,3-glucan prepared in a form easily absorbed by intestinal mucosa is able to alleviate cedar pollen-induced allergic symptoms.
Clinical implications: Orally effective SDG might greatly contribute to the resolution of epidemic medical problems of seasonal cedar pollen-induced allergy.