In Vitro Inhibition of Pathogens by Polyols: Optical Density-Based Screening and Implications for the Oral-Systemic Axis

Polyols are widely used as non-cariogenic sweeteners in foods and oral care products, yet their comparative activity against diverse oral microbes and their potential relevance to the oral–systemic axis remain incompletely defined. Here, we performed an in vitro, optical-density (OD)-based screening of four polyols—allulose, D-mannose, erythritol, and xylitol—against Streptococcus mutans, Streptococcus anginosus, Candida albicans, and Fusobacterium nucleatum. Cultures were grown with polyols at 1–20% (w/v), and OD600 was recorded at organism-specific endpoints (~24 h). Allulose, erythritol, and xylitol produced strong, concentration-dependent suppression of streptococcal growth at ≥5–10%, whereas C. albicans showed minimal changes across the tested range. F. nucleatum was highly sensitive to allulose, D-mannose, and xylitol at ≥5% (reducing OD to ≤13% of untreated control), while low concentrations of D-mannose and erythritol increased OD above control, suggesting species-specific utilization or stress responses. One-way ANOVA with Tukey’s HSD post hoc testing supported significant between-polyol differences for most concentrations in Streptococcus spp. and F. nucleatum. Collectively, these results identify polyol- and taxon-specific growth phenotypes that can inform the formulation of swallow-safe oral hygiene products and motivate follow-up work in polymicrobial biofilm models and clinical studies targeting oral inflammation and downstream systemic risk.