Firmicutes and Bacteroidetes are two major phyla of the domain Bacteria and dominant in human gut microbiota. The Firmicutes to Bacteroidetes ratio (F/B ratio) has been extensively examined for human and mouse gut microbiota. It has been shown by multiple studies that the F/B ratio is correlated with obesity and other diseases.
- Data obtained from animal models revealed consistent differences in the two major bacterial phyla with a significant increase of the Firmicutes and decrease of the Bacteroidetes levels in ob/ob compared to wild-type mice despite a similarity in their diet and activity levels (Ley et al. 2005).
- Increased ratio of Firmicutes/Bacteroidetes was found in the gut microbiota in the human population with obesity (Lay et al., 2006).
- For the Firmicutes/Bacteroidetes ratio, significant differences between infants and adults (0.4 and 10.9, respectively) and between adults and elderly (10.9 and 0.6, respectively). Notably, no significant differences were found between infants and elderly. In conclusion, F/B ratio in adults was much higher than those of infants and elderly (Mariat et al., 2009).
The Firmicutes/Bacteroidetes ratio is an index that considers high level taxonomic rank, i.e., phylum, therefore considered not reliable by later studies with more data. Meta-analyses could not find a clear trend between the F/B ratio and obesity, suggesting that the complexity of how gut microbiome modulate obesity is far more than a simple imbalance status of these two phyla (Tseng & WU, 2019).Author links open overlay panel
Last edited JC/May 5, 2020