The Effect of Probiotics on Halitosis: a Systematic Review and Meta-analysis

Although several studies have evaluated the inhibitory effect of probiotics on halitosis, findings are inconsistent. This systematic review and meta-analysis of randomized clinical trials (RCT) was conducted to summarize the evidence on the effect of probiotics on halitosis. RCT on any type of probiotic treatment with at least 2-week duration were identified through electronic databases (PubMed, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials) and hand searched between 1946 and January 17, 2017. Primary outcomes were organoleptic (OLT) scores and volatile sulfur compounds (VSC). Standardized mean difference (SMD) and 95% confidence interval (CI) were calculated. Meta-analysis was conducted to synthesize the evidence. Of the 153 articles identified, three met the inclusion criteria. Meta-analysis revealed that OLT scores (SMD = − 1.93, 95% CI − 2.85 to − 1.02, P < 0.0001) were significantly lower in subjects who received probiotics than in placebo groups, but no significant difference was observed at the VSC concentration (SMD = − 0.02, 95% CI − 2.12 to 2.07, P = 0.98). Current evidence is supportive of recommending probiotics for the management of halitosis. Based on this review, transient (average of 2 weeks) dosing with probiotics (mainly Lactobacillus strains) has a moderate effect on halitosis regarding OLT scores, but we could not confirm the effects of probiotics on the VSC reduction. The available evidence is quantitatively and qualitatively insufficient for further recommendations, especially with regard to administration strategies and pretreatment. Future studies should aim for longer follow-up and standardized administration methods to prove or refute the effect of probiotics on halitosis.