Limited, low-quality studies find probiotics provide short-term relief in proxy measures of halitosis

Reference

Huang N, Li J, Qiao X, et al. Efficacy of probiotics in the management of halitosis: a systematic review and meta-analysis. BMJ Open 2022;12(12):e060753.

Synopsis

These authors searched several databases, registries, and the grey literature to identify randomized trials that compared probiotics and placebo for the treatment of halitosis in healthy adults. Although it appears that none of the studies used the stink factor, to be included they had to report on organoleptic (OLP) scores or volatile sulfur compound levels. While widely used in research, the relationship between OLP scores and the concentration of offending gases is not known. Volatile sulfur compounds, however, represent the primary source of oral effluvia. Ultimately, these researchers included 7 small trials that enrolled between 23 and 78 participants between 19 and 70 years of age. One of the studies was at low risk of bias, one was at high risk, and the remainder were of middling quality. Six studies reported OLP scores: 1 reported a significant decrease; 1 reported a decrease at 4 weeks, but not at 8 weeks; and 4 reported no significant difference. The authors pooled the data on 5 studies and found that, overall, there was a significant reduction in OLP scores in the probiotics group compared with the placebo group. Similarly, 6 studies reported on volatile sulfur compound levels — 2 reported a decrease. After pooling those data, the overall effect was a barely statistically significant decrease. The authors found no heterogeneity among the data for these outcomes. What does this any of this mean to the afflicted person or to those living with (or having conversations with) halitosis sufferers? I haven’t a clue.