A Phylum abundance comparison between cachexia and non-cachexia patient groups. B Comparison of microbial alpha diversity: Chao1 (p = 0.21, Wilcoxon rank-sum test), Shannon index (p = 0.064, Wilcoxon rank-sum test), Simpson index (p = 0.25, Wilcoxon rank-sum test). C Non-metric multidimensional scaling (NMDS) plot comparing cachexia and non-cachexia patient groups together with a healthy Dutch cohort (NLD) of 471 subjects, based on the gut bacterial species compositions using Bray-Curtis dissimilarities (p = 0.001, r = 0.212, ANOSIM). The BMI cutoff of 25 was used to group NLD samples into “NLD_NOTobese” and “NLD_obese”. D Heatmap of differential abundant bacterial species (p < 0.05, prevalence higher than 20%). Color scale represents the row-scaled log-transformed relative abundances of species. E Potential mechanistic links between cachexia-associated gut microbiota species and serum metabolites. Spearman’s rank correlations were calculated between differentially abundant species and differentially abundant metabolites (*p < 0.05, **p < 0.01, ***p < 0.001, +FDR < 0.1, ++FDR < 0.05, +++FDR < 0.01, Spearman’s rank correlation).