Fig. 2: Differences in nasal microbiome between the hyposmic and normosmic groups.

a Boxplots illustrated α diversity indices (ACE, Chao1, and Shannon) in the hyposmic and normosmic groups, with statistical significance indicated by P-values. b Principal Coordinates Analysis (PCoA) plot based on Bray–Curtis distance visualized differences in microbial community structure between groups. Results from PERMANOVA (Adonis R² and P-value) were displayed. c Bar graph showed the proportion of variance in olfactory function explained by nasal microbiome composition, lifestyle factors, and other covariates, with significant contributors marked by ‘+’ (P < 0.05) and ‘*’ (P < 0.01). d Phylogenetic tree of nasal microbiome, highlighted genera differentially abundant between groups, with coefficient values from MaAsLin analysis: blue for higher abundance in the hyposmic group and red for lower. The outermost ring indicated the prevalence of each genus in the subjects. Significant genera were flagged with ‘+’ (FDR < 0.05) or ‘*’ (FDR < 0.01). e Boxplots of α diversity in the replication dataset with P-values. f Bar graph displayed the MaAsLin analysis coefficients for 13 genera that showed consistent associations with olfactory function between the discovery and replication datasets.