Overview of systematic reviews for the safety of probiotics on different populations and conditions

Objectives: To summarize evidence about the safety of probiotics for various clinical conditions based on recent systematic reviews. Methods: Overview of systematic reviews was conducted. Abroad and domestic databases were searched for systematic reviews that assess the safety of probiotics. “Systematic review” combined with “probiotics” or “synbiotics” were used as search terms. Reviews without systematic methodology were excluded. There was no limitation on patients and comparators. The quality of the systematic reviews was evaluated with a tool for the assessment of multiple systematic reviews (AMSTAR). Data extraction was conducted by two researchers using a standardized form. The qualitative review for safety was carried out in a way that summarized the detailed characteristics of the final selected document and the related results. Results: As a result of searching domestic and foreign literature databases, 162 out of 5,208 systematic literature review papers were ultimately selected for this study. Among the selected literature, this study was focused on 125 research papers that included detailed information regarding safety. Based on the disorders or symptoms, the research results were sorted into seven categories: 1) general population, 2) preterm and/or low birth weight infants, 3) gastrointestinal system, 4) skin and allergic diseases, 5) urinary and genital diseases, 6) respiratory diseases, and 7) others. Based on the analysis results, there were few statistically significant serious cases of injury between the probiotic group and the control group. However, as some patients with suppressed immune system or preterm infants have shown adverse events like fungemia, sepsis, liver infection, endocarditis, hepatic abscess, and bacteremia, and major caused were indicated central venous catheter contamination. Conclusions: Collectively clinical evidence for the safety of probiotics in risk patients is uncertain. Therefore, medical experts have to pay enough attention to these patients and additional research is needed.