薬理と治療

Abstract

Objectives　We previously reported that Lactobacillus acidophilus L-92 ameliorates subjective local and systemic symptoms by maintaining normal immune functions in healthy adults. The present study aimed to elucidate the effect of L-92 intake not only on subjective symptoms and immune parameters but also on intestinal immunity, including the intestinal microbiota and immunoglobulin A（IgA）levels, in healthy adults. Methods　A randomized, double-blind, placebo-controlled, parallel-group study was conducted on 180 individuals assigned to receive L-92 or placebo tablets for 8 weeks between July 2021 and September 2021. The participants received 21010× L-92 cells per day based on the same composition of the test foods. Results　The L-92 group showed the activation of plasmacytoid dendritic cells and an improvement in local symptoms, such as cough, throat discomfort, and hoarseness and subjective symptoms including fatigue, chill, and lassitude during the intervention period. The intake of L-92 also increased Bacteroides spp. and intestinal IgA. Conclusions　L-92 activates not only intestinal but also systemic immunity and alleviates typical early symptoms of viral infections in the upper respiratory tract and systemic symptoms, including the common cold, suggesting that L-92 might be a beneficial tool to enhance antiviral immunity in humans. Trial registration　https://www.umin.ac.jp/ctr; UMIN ID: UMIN000044138 （Jpn Pharmacol Ther 2022；50：1699‒707）