A bacterium from fermented plant foods that reaches the lower gut alive. Placebo-controlled trials support relief of abdominal pain and bloating in irritable bowel syndrome, better iron uptake from plant foods, and a small fall in blood cholesterol; other claims are thin. Harms are mostly mild and digestive. Evidence belongs to particular laboratory strains, not the species name. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Ferritin | 50–100 ng/mL (women), 50–150 ng/mL (men) | Iron stores; the endpoint the absorption benefit should eventually move |
| Transferrin saturation | 25–35% | Distinguishes true iron deficiency from inflammation-driven low ferritin |
| LDL cholesterol | Below 100 mg/dL; below 70 mg/dL with existing artery disease | The lipid fraction the bile salt hydrolase mechanism acts on |
| HbA1c | 5.0–5.4% | Three-month average blood sugar; the glycaemic endpoint with pooled trial support |
| High-sensitivity C-reactive protein | Below 1.0 mg/L | General inflammatory load; contextualises ferritin and tracks the inflammatory signal |
| IBS Symptom Severity Score | Below 75 (remission); a 50-point fall counts as response | The primary endpoint for the best-supported indication |
| Hydrogen and methane breath test | No established target range; track the peak value against the individual's own pre-treatment baseline | Screens for small intestinal bacterial overgrowth, the state in which this organism worsens symptoms |
Cadence: Four weeks for symptom endpoints and twelve weeks for blood markers, then every six to twelve months while supplementation continues; iron markers warrant the tightest cadence, and a four-week planned withdrawal follows the first six months.