Probiotics Effect on the Immune System
Abstract Background: Probiotics can provide health benefits to an individual by regulation of the immune system. Many clinical trials have found that probiotics can prevent upper respiratory tracts infections.Aim: To perform a systematic review and meta-analysis of available trials to investigate the effectiveness of probiotics in the prevention of upper respiratory tract infections in individuals of all ages.Methods: A database search was carried out with databases ScienceDirect, Wiley, Springer, Medline and Pubmed. Completed randomised double blind, placebo-controlled trials were selected.Selection criteria: Randomised placebo-controlled trials, with the objective of investigating probiotic effectiveness in preventing URTIs.Results: Five randomised controlled trials were included, as the extracted data could be meta-analysed. This included a total of 785 participants of different age groups, children and adults. It was found that probiotics were better compared to placebo in reducing the number of participants who experienced acute upper respiratory tract infections. Probiotics were found to reduce the mean duration of acute URTI episodes, antibiotic use compared to placebo and URTI or cold related absence. Side effects and adverse effects were found to be minor and not statistically significant.Conclusions: Probiotics were found to be better in reducing the number of participants who experienced acute URTI, the average duration per episode of acute URTI, use of antibiotics in URTI related cases and absence due to URTI. Side effects were found to be minor, making probiotics a good candidate for clinical use. This shows that probiotics are effective in preventing acute URTIs. However, due to limited studies and small sample size, the results are subjected to bias and should be interpreted with care.