Alleviation of seasonal allergic symptoms with superfine β-1,3-glucan: A randomized study

Background The incidence of allergic symptoms to cedar pollen has reached epidemic proportions in Japan. Intravenous injection of β-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 β-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 β-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 β-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 β-1,3-glucan. Although SDG reduced allergic symptoms, the oral uptake of nondispersed β-1,3-glucan produced no clinical effects, despite the identical amount of β-1,3-glucan in both preparations. Conclusion We postulate that orally taken β-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.