Although the efficacy of probiotics has been extensively studied in hepatic encephalopathy (HE), the results remain controversial. The objective of this study is to identify and update the association between probiotics and HE.

Up to December 2014, we searched Medline, Embase, Web of Science, Cochrane CENTRAL, and SinoMed of China for all relevant articles about probiotics and HE. Jadad score was used to evaluate the quality of studies. Pooled relative risk (RR), publication bias and heterogeneity were assessed.

Nine studies met the inclusion criteria. Probiotics was associated with improvement of minimal HE and prophylaxis of overt HE [RR 1.52; 95% confidence intervals (95% CI) 1.00–2.33]. Studies with probiotics showed reduction of ammonia concentration [standard mean difference (SMD) –0.32, 95% CI –0.54 to –0.11]. Probiotics could reduce physical and psychosocial sickness impact profile (SIP) score with weight mean difference (WMD) –3.13 (95% CI –4.10 to –2.17) and WMD –3.50 (95% CI –4.91 to –2.08), respectively. Similar result was obtained with total SIP score (WMD –4.83; 95% CI –6.24 to –3.43). Reduction of severe adverse events, defined as minimal HE developing into overt HE, hospitalizations, infections or unrelated emergency room (ER) visits, was observed in HE with probiotics (RR 0.59; 95% CI 0.39–0.90).

Our pooled results indicated that probiotics was associated with improvement of minimal HE, prophylaxis of overt HE, and reduction of SIP score and severe adverse events. Large well-designed randomised controlled trials are needed to confirm these results.