Parasutterella excrementihominis is a Gram-negative, obligate anaerobic bacterium within the Betaproteobacteria class that has gained attention as an emerging biomarker across metabolic, inflammatory, and endocrine conditions. Despite its relatively recent characterization, Parasutterella appears prominently in MR studies and dietary intervention trials.
Metabolic Functions
Succinate Production
- P. excrementihominis is a succinate producer rather than a classical SCFA (butyrate/propionate) producer.
- Succinate serves as both a metabolic intermediate and an immune signaling molecule, activating succinate receptor 1 (SUCNR1/GPR91) on dendritic cells and macrophages.
- This positions Parasutterella as a modulator of innate immune responses through its metabolic output.
Bile Acid Metabolism
- Implicated in bile acid transformation pathways, potentially influencing the enterohepatic circulation of bile acids.
- Its role in bile acid metabolism connects to broader effects on cholesterol handling and lipid homeostasis.
Lipid Associations
- MR analyses link Parasutterella to higher ApoB and LDL-cholesterol levels [teng 2024 gut microbiome lipids mr], suggesting a causal role in lipid metabolism.
- Decreased following ketogenic diet intervention in CRC models [gao 2026 ketogenic diet fxr nfkb crc], consistent with dietary fat composition influencing its abundance.
Disease Associations
Cardiovascular Disease
- MR evidence identifies Parasutterella as protective against coronary artery disease (OR=0.936) [dai 2024 gut microbiota cvd bidirectional mr].
- This protective CVD association exists despite its positive correlation with LDL-C, suggesting complex mechanisms beyond simple lipid effects.
Endometriosis
- Enriched in mouse models of endometriosis, identified as one of ten characteristic bacteria with high LDA scores in endometriotic mice [ni 2020 fecal metabolomics gut microbiota endometriosis mice].
- Also enriched alongside Bifidobacterium in endometriosis mouse models [yuan 2018 endometriosis induces gut microbiota alterations mice].
Autoimmune Thyroiditis
- Significantly increased after 4 weeks of gluten-free diet in autoimmune thyroiditis patients (p=0.008), alongside increases in Desulfobacterota and Proteobacteria [rodziewicz 2024 gluten free diet microbiome autoimmune thyroiditis].
- Its increase on GFD connects to emerging roles in tryptophan metabolism and gut-immune interactions.
IBD
- Altered in inflammatory bowel disease, with context-dependent changes in Crohn's disease versus ulcerative colitis.
- Its Proteobacteria lineage places it in a phylum that is generally expanded in IBD-associated dysbiosis.
Dietary Responsiveness
Parasutterella is notably responsive to dietary interventions:
- Decreased by lactobacillus supplementation [xie 2025 cholesterol crc simvastatin lactobacillus].
- Decreased by ketogenic diet [gao 2026 ketogenic diet fxr nfkb crc].
- Increased by gluten-free diet [rodziewicz 2024 gluten free diet microbiome autoimmune thyroiditis].
Connections
- cardiovascular disease -- MR-identified protective factor against CAD
- endometriosis -- enriched in endometriosis mouse models
- inflammatory bowel disease -- altered in IBD as a Proteobacteria member
- bile acids -- involved in bile acid transformation pathways
- dysbiosis -- responsive to dietary interventions and probiotic supplementation
- tryptophan -- emerging role in tryptophan metabolism and immune modulation
- cholesterol -- MR-linked to ApoB and LDL-C levels