Firmicutes to Bacteroidetes ratio (F/B ratio)

Firmicutes/Bacteroidetes ratio refers to the quotient of the relative abundances of Firmicutes (a phylum of Gram-positive bacteria) and Bacteroidetes (a phylum of Gram-negative bacteria) in the human gut microbiome. This ratio is widely studied as a broad marker of gut health and dysbiosis, with particular links to obesity—a higher ratio is often observed in obese individuals, while a lower ratio is associated with inflammatory bowel disease. The ratio is not a molecular drug target but rather a descriptive parameter measured via sequencing of stool samples. It is subject to considerable biological and methodological variability, and while it offers a simple overview of microbiome composition, its utility as a clinically reliable biomarker remains debated and context-dependent[1][3][7]. For structured data extraction, this entry should be flagged as a metric/biomarker, not a molecule or classical drug target.

Other names

F/B ratioFirmicutes:Bacteroidetes ratioFirmicutes-to-Bacteroidetes ratio

Altering microbiota composition to restore balance (e.g., probiotics increase Bacteroidetes or decrease Firmicutes depending on species) Modulation of fermentation and SCFA production via dietary interventions (fiber increases Bacteroidetes) Immunomodulation via induced changes in microbiome composition