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

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.

Postbiotics: The concept and their use in healthy populations

“…However, the study product significantly reduced influenza incidence in the subjects aged < 40 years (n = 1,077). No serious adverse events were reported (22).…”

Resistance, Tolerance, Virulence and Bacterial Pathogen Fitness—Current State and Envisioned Solutions for the Near Future

“…A randomized controlled trial was performed by Satomi et al (2021) in order to investigate whether a combination of heat-killed Levilactobacillus brevis KB290 (KB290) and β-Carotene (KB290 + βC) could reduce the incidence of influenza and common colds as well as alleviate clinical symptoms in healthy Japanese adults. They demonstrated, in a first large-scale human clinical trial, that these combined food components might be a possible candidate for protection against seasonal influenza virus infections in humans aged <40 years [ 212 ].…”

Identification and Safety Assessment of Enterococcus casseliflavus KB1733 Isolated from Traditional Japanese Pickle Based on Whole-Genome Sequencing Analysis and Preclinical Toxicity Studies

“…According to the definition suggested by the Food and Agriculture Organization (FAO)/World Health Organization (WHO), health-promoting LAB are designated as probiotics and are considered non-pathogenic live microorganisms that confer health benefits to the host when administered in adequate amounts [1]. Non-viable LAB have also recently attracted interest as potential probiotics [2,3]. Most LAB employed as probiotics belong to the genera Lactobacillus and Enterococcus [4].…”