薬理と治療

Abstract

Objectives The aim of the present study was to elucidate the effect of Lactobacillus acidophilus L-92 intakes on upper respiratory tract subjective symptoms and immune parameters（NK cell activity and salivary IgA）in healthy subjects by a randomized, double-blind, placebo-controlled, parallel-group comparison study. Methods Subjects were divided into 2 groups which consumed a L-92（2⊠1010 cells╱drink）containing drink or placebo once a day for 8 weeks. The discomfort of upper respiratory tract was recorded weekly by the subjects throughout the study, and medical examinations to analyze immune parameters and to assess safety parameters were carried out at weeks 0（baseline）, 4, and 8.Results Throat and cough discomfort scores were significantly elevated in the placebo group but not in the L-92 group. A significant difference in baseline changes in throat discomfort scores was also observed between the placebo and L-92 groups. Additionally, the change in NK cell activity in peripheral blood was significantly higher in the L-92 group compared with the control throughout the study period. Conclusions These results suggest that L-92 ingestion enhances NK cell activity and may reduce throat discomfort, which occurs in the early stage of the common cold. Safety parameters did not differ significantly between the groups.