Plant fibers human enzymes cannot break down and gut bacteria readily can. They reliably increase those bacteria and modestly increase stool frequency in normal or sluggish bowels. Blood sugar improves in people whose blood sugar is already impaired, hardly at all in others. Weight, waistline, cholesterol, and inflammation move favourably but slightly. Gas sets the ceiling on intake. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Fasting glucose | 75–86 mg/dL | Primary quantified endpoint; largest effect size of any outcome |
| HbA1c | 4.8–5.4% | Integrates the glycemic effect over the trial-relevant window |
| Fasting insulin | 2–5 µIU/mL | Detects insulin sensitivity gains that precede any glucose change |
| Triglycerides | Below 80 mg/dL | One of two lipid fractions the meta-analyses found responsive |
| LDL-C and ApoB | LDL-C below 80 mg/dL; ApoB below 80 mg/dL | The other responsive lipid fraction; particle count adds information cholesterol mass does not |
| hs-CRP | Below 0.5 mg/L | Tracks the low-grade inflammation signal, the weakest and most contested benefit |
| Red blood cell magnesium | 5.0–6.5 mg/dL | Absorption of this mineral rises with fructans; confirms the effect is real in the individual |
| 25-hydroxyvitamin D | 40–60 ng/mL | Governs whether improved calcium absorption translates into bone mineral |
| Bristol Stool Form Scale type | Type 3–4 | The bowel-function endpoint, and the earliest visible signal of effect |
Cadence: Baseline before starting; metabolic and inflammatory markers repeated at 12 weeks, then every 6–12 months on stable dosing. Mineral and vitamin D testing annually unless supplementation changes. Stool form self-recorded daily for one week at baseline and again at 4 weeks.