Effectiveness of kuromoji (lindera umbellate thunb.) extract in the prevention of influenza infection -A randomized,double-blind,placebo-controlled,parallel-group study

Abstract

Objectives Although vaccination is effective method to prevent influenza infection, current influenza vaccines have inadequate efficacy in general populations. For these reasons a supplement that prevent influenza infection is keenly anticipated. In basic research, it is demonstrated that kuromoji (Lindera umbellate Thunb.) extract has an effectiveness preventing influenza infection. The aim of this study was to assess whether kuromoji extract has a protective effect on influenza infection in clinical settings. Methods In a randomized, double-blind, placebo-controlled, parallel-group study, 135 adult volunteers, they are healthy nursing staff and are met inclusion and exclusion criteria, partici-pated in this study. Sixty-seven participants received test candy (containing 67 mg/day of kuromoji extract), and another 68 participants received placebo candy. Results Test candy significantly reduced influenza infection after 12 weeks compared with placebo candy. Conclusions This is the first clinical study to assess the effectiveness of kuromoji extract in the prevention of influenza infection. Our results suggest that kuromoji extract is a safe supplement for the prevention of influenza infection.