A randomized, double-blind, placebo-controlled study of Ten-Cha (Rubus suavissimus) on house dust mite allergic rhinitis

Objective: Self-care with Ten-Cha is the most common complementary alternative medicine for allergic rhinitis in Japan, but evidence for an actual therapeutic effect is lacking. The purpose of the study was to investigate the effect of Ten-Cha (Rubus suavissimus) on house dust mite allergic rhinitis. Methods: The study was performed in the otolaryngology departments of 5 facilities (Chiba University, Kagoshima University, Fukui University, Okayama University, and Nippon Medical School) from July to December 2009. A randomized double-blind study was performed with central enrollment and allocation. The subjects ingested 400. mg of Ten-Cha extract or placebo (3 capsules/day) daily for 4 weeks as a food intervention. The number of subjects was chosen with anticipation of an effect equivalent to that of mast cell-stabilizing drugs. A nasal allergy diary-based symptom score and a QOL score were used for evaluation. Results: The Ten-Cha and placebo groups included 47 and 42 subjects, respectively. The improvement rates for sneeze, nasal discharge, nasal obstruction, and symptom scores were greater in the Ten-Cha group than in the placebo group throughout the intervention period, and the effect tended to increase with time in the Ten-Cha group. However, the differences between the groups were not significant. QOL was not significantly improved in either group. Conclusion: Ingestion of Ten-Cha had an effect on allergic rhinitis, but the effect of Ten-Cha was limited and did not differ significantly from placebo. These results suggest that Ten-Cha does not exhibit an effect equivalent to mast cell-stabilizing drugs at the dose used in this study.