A randomised, double-blind clinical study into the effect of zinc citrate trihydrate toothpaste on oral plaque microbiome ecology and function.

Summary

In a 6-week double-blind RCT (n=115), zinc citrate toothpaste shifted plaque microbiome composition (e.g., increased Veillonella, decreased Fusobacterium taxa) and reduced predicted glycolysis while increasing pathways linked to gum and systemic health (lysine biosynthesis, nitrate reduction). This provides in-vivo evidence that zinc-containing toothpaste beneficially modulates plaque microbiome ecology and function.

Key Findings

• Zinc toothpaste altered plaque bacterial communities at community and species levels compared to control.
• Species-level increases in Veillonella and decreases in a Fusobacterium taxon were observed.
• Predicted metagenomic/transcriptomic analyses suggested reduced glycolysis and increased lysine biosynthesis and nitrate reduction.

Clinical Implications

Supports recommending zinc-containing toothpaste for patients at risk of gingivitis or caries; underscores the need to evaluate long-term clinical outcomes alongside microbiome endpoints.

Limitations

• Functional inferences were prediction-based rather than from shotgun metagenomics/metatranscriptomics or direct metabolomics.
• Short 6-week duration without hard clinical endpoints (e.g., incident caries/gingivitis).

Future Directions

Incorporate shotgun -omics and metabolomics, extend to longer-term trials with clinical endpoints, and assess systemic effects (nitrate reduction) on cardiometabolic health.