Psyllium seed husk is a gel-forming plant fiber that thickens gut contents and survives to the stool undigested. It lowers cholesterol, steadies blood sugar where control has already slipped, softens stools and firms loose ones, and slightly lowers the upper blood pressure number. The effects are consistent rather than large, and present only while it is taken. (Full Review)
| Marker | Target | Why |
|---|---|---|
| LDL Cholesterol | < 70 mg/dL (< 1.8 mmol/L) | Primary lipid target psyllium moves |
| Apolipoprotein B | < 80 mg/dL; < 60 mg/dL if cardiovascular risk is high | Counts artery-clogging particles directly; lowered independently of LDL |
| HbA1c | 4.8–5.4% | Integrates the glycemic effect over three months |
| Fasting Glucose | 75–86 mg/dL (4.2–4.8 mmol/L) | Detects the effect earliest; predicts who benefits at all |
| Blood Pressure | < 120/80 mmHg seated | Captures the small systolic effect; larger from a high baseline |
| Serum Ferritin | 50–150 ng/mL (men, postmenopausal women); 30–100 ng/mL (premenopausal women) | Screens for iron depletion during long-term high-dose viscous fiber |
| Thyroid Stimulating Hormone | 0.5–2.0 mIU/L, if taking thyroid hormone | Detects under-replacement from delayed levothyroxine absorption |
| Serum Lithium | 0.6–0.8 mmol/L, if prescribed | Documented interaction with loss of therapeutic level |
| Serum 25-Hydroxyvitamin D | 40–60 ng/mL (100–150 nmol/L) | Fat-soluble vitamin absorption is theoretically reduced by bile-acid binding |
Cadence: Baselines before starting; lipids and blood pressure rechecked at 8 weeks, HbA1c at 12 weeks, narrow-therapeutic-index drug levels at 4 to 8 weeks after starting or any dose change; thereafter every 6 to 12 months, with ferritin annually on long-term high doses