Dietary Sulfur Compounds and Halitosis: Bridging Food Science, Microbial Metabolism, and Oral Health: A Comprehensive Review.

Intraoral halitosis is predominantly caused by anaerobic microbes within the tongue biofilm that break down sulfur-containing amino acids, especially cysteine and methionine, to volatile sulfur compounds (VSCs). In addition to microbial activity, there is growing evidence to suggest that dietary factors are able to influence VSC formation by affecting substrate availability, redox equilibrium, and oral ecological stability and that some of these effects are due to extraoral metabolic activity. This review integrates food chemistry, microbial ecology, and oral health to explain how dietary exposures can interact with the oral microbiome to trigger and maintain halitosis. We synthesize current evidence on tongue biofilm ecology, key microbial taxa and metabolic pathways, and the modifying roles of salivary flow, periodontal inflammation, and common beverages and condiments. Diagnostic approaches are discussed with a mechanistic viewpoint, which has focused on combined organoleptic, gas specific analysis, tongue biofilm imaging, and selective provocation testing. Comprehensively, halitosis is presented as a diet modifiable, ecology-driven disease, the diagnostics of which should be guided by phenotype, and the intervention based on microbiomes and tailored care plans should be sustainable so that evidence-based functional foods and personalized care plans can be developed.