Abstract

Objectives: We compared the salivary proteome and metaproteome of individuals with real-world dietary patterns differing in fiber intake (i.e., high- versus low-fiber intake) to examine whether their diet was associated with distinct molecular signatures in saliva. Materials and methods: Sixteen participants from a cross-sectional study were classified into high-fiber (n = 8) and low-fiber (n = 8) intake groups based on dietary assessment. Although these groups corresponded to vegan and omnivorous patterns, respectively, classification was based on fiber intake. Groups were matched for age, sex, socioeconomic status, while major dietary differences inherent to vegan and omnivorous patterns were explicitly considered in the interpretation. Stimulated whole saliva was collected under standardized fasting conditions. Human proteomic and microbial metaproteomic analyses were performed using bottom-up DIA-PASEF. Differentially abundant proteins, enriched pathways, and metaproteomic profiles were identified using bioinformatic analyses. Results: From 3,332 identified proteins, 1,566 were quantifiable, and 66 were differentially abundant between groups (FDR [False Discovery Rate] < 0.05). Multivariate analyses revealed separation according to dietary patterns differing in fiber intake: high-fiber exhibited enrichment of homeostasis, lipid metabolism, and cytoprotective pathways, with increased abundance of PRP-1/2, CA6, APOA1, and HYOU1. Low-fiber showed enrichment of immune and oxidative stress pathways, with higher SOD1, GPX1, ANXA2, ANXA8, and S100A8. Metaproteomics analysis revealed no major taxonomic differences but greater interindividual variability in the low-fiber intake group. Conclusion: Dietary patterns characterized by different dietary fiber intake appear associated with distinct salivary proteomic signatures. Although the contribution of other co-occurring dietary factors cannot be excluded, these findings, based on a small, highly selected cohort, suggest that fiber-rich dietary patterns may support oral homeostasis through host-driven molecular pathways rather than major shifts in microbial composition. Clinical relevance: Our findings strengthen the rationale for considering dietary patterns with high-fiber intake not only as a systemic health determinant but also as a modulator of salivary molecular functions relevant to oral disease prevention and personalized care.