Is Probiotic and Synbiotic Supplementation Effective on Immune Cells? A Systematic Review and Meta-analysis of Clinical Trials

Probiotics and prebiotics: potential prevention and therapeutic target for nutritional management of COVID-19?

Scientists are working to identify prevention/treatment methods and clinical outcomes of coronavirus disease 2019 (COVID-19). Nutritional status and diet have a major impact on the COVID-19 disease process, mainly because of the bidirectional interaction between gut microbiota and lung, that is, the gut-lung axis. Individuals with inadequate nutritional status have a pre-existing imbalance in the gut microbiota and immunity as seen in obesity, diabetes, hypertension and other chronic diseases. Communication between the gut microbiota and lungs or other organs and systems may trigger worse clinical outcomes in viral respiratory infections. Thus, this review addresses new insights into the use of probiotics and prebiotics as a preventive nutritional strategy in managing respiratory infections such as COVID-19 and highlighting their anti-inflammatory effects against the main signs and symptoms associated with COVID-19. Literature search was performed through PubMed, Cochrane Library, Scopus and Web of Science databases; relevant clinical articles were included. Significant randomised clinical trials suggest that specific probiotics and/or prebiotics reduce diarrhoea, abdominal pain, vomiting, headache, cough, sore throat, fever, and viral infection complications such as acute respiratory distress syndrome. These beneficial effects are linked with modulation of the microbiota, products of microbial metabolism with antiviral activity, and immune-regulatory properties of specific probiotics and prebiotics through Treg cell production and function. There is a need to conduct clinical and pre-clinical trials to assess the combined effect of consuming these components and undergoing current therapies for COVID-19.

The effect of probiotics, parabiotics, synbiotics, fermented foods and other microbial forms on immunoglobulin production: a systematic review and meta-analysis of clinical trials

The aim of this systematic review and meta-analysis was to evaluate the effect of probiotics, parabiotics, synbiotics, fermented foods and other microbial forms on immunoglobulin production. We searched PubMed, Scopus, Web of Science, National Institute of Health Clinical Trials Register, and Cochrane Central Register of Clinical Trials, up to February 2020. All clinical trials that investigated the effects of oral intake of probiotics, parabiotics, synbiotics, fermented foods and other microbial forms on immunoglobulin (Ig)A, IgE, Japanese cedar pollen (JCP)-specific IgE, IgG, and IgM, for a duration of >7 days were included. Fifty-nine studies met the inclusion criteria, of these 54 studies were included in the analysis. The results indicated a significant increase in salivary IgA secretion rate (SMD = 0.21, 95% CI 0.02-0.39), while no significant effect was observed on other Igs. In conclusion, mentioned supplementation induced a small but significant effect on salivary secretion rate of IgA.