A food-grade bacterium sold as a live culture. The evidence attaches to individual commercial strains, not the species name. Best supported: protection against diarrhoea caused by antibiotics, and softening of hard stools. Very safe in healthy adults, genuinely dangerous with weakened immune defences, a long-term tube into a vein, or severe acute illness. Much positive work was company-funded. (Full Review)
| Marker | Target | Why |
|---|---|---|
| High-sensitivity C-reactive protein (hs-CRP) | Below 1.0 mg/L, ideally below 0.5 mg/L | Tracks the low-grade inflammation that fell alongside joint symptom improvement |
| Bristol Stool Form Scale score | Types 3 to 4 on at least 75% of bowel movements | The primary endpoint on which the constipation trials were positive |
| Complete blood count with differential | Absolute neutrophils 1.5 to 4.0 × 10⁹/L; absolute lymphocytes 1.5 to 3.0 × 10⁹/L | Confirms the immune competence that separates negligible from real invasive-infection risk |
| Faecal calprotectin | Below 50 µg/g | Detects bowel-wall inflammation that would reframe symptoms as disease rather than an unbalanced gut community |
| Haemoglobin A1c (HbA1c) with fasting glucose | HbA1c 4.8–5.4%; fasting glucose 75–86 mg/dL | Captures the carbohydrate load added by sugar-sweetened fermented-milk vehicles |
Cadence: Symptom baseline repeated at four weeks and high-sensitivity C-reactive protein at three months; thereafter the blood count and inflammatory marker are reviewed every six to twelve months, or sooner when immune status, medication or device status changes.