Effects of Heat-Killed Levilactobacillus brevis KB290 in Combination with β-Carotene on Influenza Virus Infection in Healthy Adults: A Randomized Controlled Trial

Shohei Satomi,Hiroyuki Suganuma,Kazuhiko Fujisawa,Naoko Waki,Shigenori Suzuki,Chinatsu Arakawa

doi:10.3390/nu13093039

Abstract

Influenza, a seasonal acute respiratory disease caused primarily by the influenza virus A or B, manifests with severe symptoms leading to considerable morbidity and mortality and is a major concern worldwide. Therefore, effective preventive measures against it are required. The aim of this trial was to evaluate the preventive effects of heat-killed Levilactobacillus brevis KB290 (KB290) in combination with β-carotene (βC) on influenza virus infections in healthy Japanese subjects aged between 20 and 59 y throughout the winter season. We performed a randomized, double-blind, placebo-controlled, parallel-group trial from 16 December 2019 to 8 March 2020, comparing KB290 + βC beverage with placebo beverage. The primary endpoint was the incidence of influenza based on a doctor’s certificate. The incidence of influenza was not significantly different between the two groups. However, the subgroup analysis showed a significant difference between the two groups (influenza incidence: the KB290 + βC group 1.9%, and the placebo group 3.9%) in the subgroup of subjects aged ˂40 y, but not in the subgroup of subjects aged ≥40 y. The results of this trial suggest that the combination of KB290 and βC might be a possible candidate supplement for protection against the seasonal influenza virus infection in humans aged <40 y, although further clinical studies are needed to confirm the concrete preventive effect of this combination on influenza.

Highlights

Seasonal influenza is an acute respiratory disease that circulates periodically worldwide [1]
It is important to enhance host immune responses and resistance to influenza viruses in daily life. Vitamins such as vitamin A (VA) or vitamin D have been studied for their effects on the immune system and immune function as well as their protective effects against influenza infection [6,7,8,9]
KB290 + βC group and 8 in the placebo group did not take the intervention for personal reasons, indicating that 1097 and 1092 in the KB290 + βC and placebo groups, respectively, took their respective experimental beverages at least once throughout the trial period

Summary

Introduction

Seasonal influenza is an acute respiratory disease that circulates periodically worldwide [1]. Influenza type A and B viruses (IAV and IBV, respectively) are a public health concern, causing clinical symptoms such as sudden onset fever, myalgia, headache, malaise, cough, sore throat, nasal congestion, and abdominal pain [2,3]. It is important to enhance host immune responses and resistance to influenza viruses in daily life. Vitamins such as vitamin A (VA) or vitamin D have been studied for their effects on the immune system and immune function as well as their protective effects against influenza infection [6,7,8,9]. Lactic acid bacteria (LAB) have been reported to exert immunomodulatory effects on the respiratory tract and protect the host against IAV infections [10,11].

Methods

Results

Conclusion