Psyllium Fiber for Constipation
Psyllium fiber is an effective, well-established treatment for chronic constipation, working as a bulk-forming laxative that softens stool and increases bowel-movement frequency. The evidence is moderate and consistent rather than definitive, and benefits are smaller in older adults; it must be taken with plenty of water.
Why this grade7-layer evidence engine
This claim earns a moderate (A-tier) grade because multiple lines of evidence converge in the same direction. An updated 2022 meta-analysis of 16 randomized trials (PMID 35816465) ranked psyllium as the most effective fiber type, with the psyllium subgroup significantly increasing stool frequency by roughly 3 bowel movements per week, improving stool consistency, and producing a strong treatment response (RR 1.82). An older head-to-head trial (PMID 9663731) also found psyllium superior to docusate sodium for softening stool, and a placebo-controlled trial in type 2 diabetes (PMID 30219432) showed it improved constipation symptoms.
Regulators and major clinics reinforce this. The US FDA recognizes psyllium as a soluble-fiber and OTC bulk-forming laxative ingredient, the UK NHS classifies ispaghula husk as a laxative that bulks and softens stool over 2-3 days, the WHO monograph endorses its traditional use for occasional constipation, and the Mayo Clinic calls fiber supplements the gentlest, bulk-forming option. This regulatory and clinical agreement is why confidence is relatively high.
The grade stays at moderate rather than strong for real reasons. The pivotal psyllium subgroup rests on only 3 trials with notable heterogeneity, and a 2025 meta-analysis in older adults (PMID 40647069) found no significant improvement in stool frequency, though it did reduce laxative use. Bloating and flatulence are common, optimal effect needs adequate dosing (over ~10 g/day) for at least 4 weeks, and psyllium must be taken with enough fluid to avoid choking or obstruction and can delay absorption of co-taken oral medications.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.7
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status