Firmicutes

Definition

Phylum of Gram-positive dominant bacteria in the human intestinal microbiome. Firmicutes include lactic acid bacteria, Clostridium, and Faecalibacterium.

How it works

Firmicutes represent around 60-70% of the intestinal flora and play key roles in fiber fermentation and short-chain fatty acid production, particularly butyrate. This phylum includes very beneficial bacteria such as Faecalibacterium prausnitzii but also pathogenic species like some Clostridium. The Firmicutes/Bacteroidetes ratio is an important health indicator: an overly elevated ratio is associated with obesity and inflammation.

Role

Ferments fibers and produces essential metabolites for energy and intestinal health.

Examples

• Faecalibacterium prausnitzii, Lactobacillus, Clostridium clusters IV and XIVa, Roseburia

Recommendations

Consume a lot of soluble fibers (oats, apples, legumes) to nourish beneficial Firmicutes. Seek a balance with Bacteroidetes by varying your food sources.

Key takeaway

Firmicutes are essential, but their balance with Bacteroidetes determines microbiome health.

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