Probiotics in prevention and treatment of COVID-19: a systematic review of current evidence

Abstract

Introduction. Clinical evidence suggests that certain probiotics may help treat and prevent viral infections. To date, the effectiveness of probiotics in the alleviation of COVID-19 has not been established. The aim of this systematic review was to assess the role of probiotics in the prevention and treatment of COVID-19. Materials and methods. An extensive search of four electronic databases was performed which included Embase, Scopus, Web of Science, and PubMed from November 2019 to June 2022. After reviewing the references list of related articles additional studies were identified. A multiple combination of keywords validated by MESH were used to search the databases. Study selection was performed according to an inclusion and exclusion criteria. Results. Twenty-three articles met the study inclusion criteria. Six articles were conducted in vitro while the remaining studies were conducted in the human population (in vivo). The type of probiotic was defined in eighteen studies. There were two studies that used supplements (vitamins, herbals, minerals, etc.) in addition to probiotics. The largest sample size was 445 850 participants which were from a study that used an application-based survey. The majority of studies found that probiotics had a positive effect on the COVID-19 disease. The benefits included early remission of COVID-19 symptoms and a shorter duration of sickness (10 studies), lower mortality rates (3 studies), and decreased hospitalization and length of stay (3 studies). Six in vitro studies found that probiotics were beneficial against SARS-CoV-2 through antiviral effects. There were only two studies that found probiotics to be ineffective or caused negative effects when consumed in COVID-19 patients. Conclusion. Available evidence supports the antiviral role of probiotics on prevention and treatment of COVID-19. The antiviral potential of Lactobacillus paracasei metabolite PlnE and PlnF against SARS-CoV-2 may explain the effectiveness of probiotics on COVID-19.