A fibre-eating colon bacterium that cannot be bought and has never been given to a person under study. Carrying more of it tracks with stronger grip, milder bowel and nerve disease, and less artery plaque; one study tracks worse blood fats in men. Diet is the only lever, it works unreliably, and the cost is gas and bloating. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Roseburia inulinivorans relative abundance (stool) | No established target; change from own baseline, and whether detectable at all | The only direct read-out of the target |
| Faecal short-chain fatty acids, butyrate share | Butyrate 15–20% of total; total 50–100 µmol/g wet stool | Functional output of the whole butyrate-producing guild |
| Faecal calprotectin | Below 50 µg/g | Detects the intestinal inflammation that both depletes this species and worsens fibre tolerance |
| High-sensitivity C-reactive protein (hs-CRP) | Below 0.5 mg/L | Systemic inflammation; abundance is lowest in patients with raised values |
| HbA1c | 4.8–5.3% | Glycaemic control, the domain with the largest depletion literature |
| Fasting triglycerides | Below 80 mg/dL (0.9 mmol/L) | Addresses the one cohort where higher abundance tracked worse lipids in men |
| Dominant-hand grip strength | Men 40 kg or above, women 25 kg or above | The single endpoint with a species-specific human signal |
| Dietary fibre intake (3-day record) | 30–40 g/day | The strongest predictor of whether any substrate strategy will work |
| Faecal pH | 6.0–6.5 | Cheap proxy for the overall fermentation rate |
Cadence: Baseline panel, then weekly symptom checks through titration; repeat stool metagenome and faecal short-chain fatty acids at 3 months; full panel at 6 months, then every 6–12 months.