Faecalibacterium prausnitzii
Also called: F. prausnitzii, F. prau
Faecalibacterium prausnitzii is one of the most abundant bacterial species in healthy adult guts, making up 5 to 15 percent of the colon microbiome. It is a major butyrate producer and has anti-inflammatory effects on the gut lining. Low levels are consistently found in IBD, IBS, type 2 diabetes and obesity. Diverse fibre intake, especially soluble fibre, is the best way to support it.
Why it matters
F. prausnitzii is what microbiome researchers call a 'keystone species', its abundance shapes the wider microbial community. It produces butyrate, which colonocytes use as primary fuel. It also produces specific anti-inflammatory metabolites that calm the local immune response. People with healthy gut function tend to have high F. prausnitzii. People with active gut disease tend to have low levels, often the first marker that drops.
Why levels drop
- Inflammatory bowel disease (Crohn's especially).
- Repeated antibiotic courses.
- Low fibre, processed-food-heavy diets.
- Heavy alcohol use.
- Stress and chronic short sleep.
- Ageing (gradual decline).
- C-section birth and formula feeding (in infants).
How to support it
- Eat 30+ different plant foods per week (the Tim Spector / British Gut Project finding).
- Resistant starch (cooked-and-cooled potato/rice, slightly green bananas) feeds it especially well.
- Soluble fibre from oats, kiwi, chia, psyllium.
- Polyphenol-rich foods (berries, dark chocolate, olive oil).
- Reduce ultra-processed food. Strongly associated with low F. prau.
- Avoid unnecessary antibiotic courses; recovery can take 6 months.
Can you take F. prausnitzii as a probiotic?
Not yet, easily. F. prausnitzii is extremely oxygen-sensitive and dies during processing. It is being developed as a 'next-generation probiotic' but is not yet commercially available in stable form. The realistic path is to feed your existing F. prau through diet rather than try to add more from a bottle.
Common questions
- Should I get my F. prau levels tested?
- Most consumer microbiome tests report it. Levels fluctuate day-to-day with diet, so a single snapshot has limited value. More useful for tracking changes over months after a deliberate diet change.
- Is F. prau the same as Akkermansia?
- Different species, both keystones. Akkermansia lives in the mucus layer and produces propionate. F. prau lives in the colon lumen and produces butyrate. Both are markers of gut health; both decline in similar conditions.
- Why does my microbiome test show low F. prau?
- Common causes: low-fibre diet, recent antibiotics, IBD, chronic alcohol use, or simply natural variation. Add fibre variety and resistant starch for 4-8 weeks then retest.