A Chewing Gum Containing Heyndrickxia coagulans SNZ1969^® and Volatile Sulphur Compounds: An Exploratory Secondary...

Background: Chewing gum may reduce oral malodor through salivary stimulation and may also serve as a carrier for oral probiotics. Evidence on Heyndrickxia coagulans in this setting is lacking. Methods: This exploratory secondary analysis used data from a randomized, blinded, placebo-controlled study in which 52 healthy adults were assigned to a sugar-free gum with H. coagulans SNZ1969^® or to a matched placebo gum for four weeks. Hydrogen sulphide (H₂S) and methyl mercaptan (CH₃SH) were measured by OralChroma™ at baseline (T₀), during intervention (T₁-T₂), and one week after gum discontinuation (T₃). Dental plaque 16S rRNA profiles from the parent trial were re-analysed in relation to VSC values. Results: Forty-four participants completed follow-up. H₂S and CH₃SH concentrations did not differ between probiotic and placebo groups at any visit, and changes from baseline were also similar between arms. In the probiotic group, H₂S was lower than baseline at T₂ (p = 0.008) and T₃ (p = 0.031), but this within-arm decrease was not greater than the change seen with placebo. Taxon-level analyses suggested nominal associations with taxa plausibly linked to sulphur metabolism, mainly for H₂S, but no association survived false-discovery-rate correction. Conclusions: The probiotic gum did not show a statistically significant additional effect on VSC concentrations compared with the placebo gum. The within-arm H₂S decrease and microbiome signals are exploratory and require confirmation in trials designed for participants with clinically established halitosis.