Prebiotics for Irritable Bowel Syndrome
Verdict: Counter-Evidence
Across 3 PubMed studies, the evidence for Prebiotics in Irritable Bowel Syndrome grades Tier D — counter-evidence. High-quality evidence indicates it is not effective (or is harmful) for this use.
D 🔴 D Counter-Evidence Counter-Evidence
Why this grade7-layer evidence engine
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Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditableRaw score 0.41
D
C
B
A
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← counter-evidence / ineffectiveeffective / strong evidence →
Final grade
D · Counter-Evidence
Confidence
81%
Highly consistent evidence
Evidence level
E2
Multiple high-quality MAs (≥2 independent, consistent)
▸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 = 0.412
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 無高階證據可裁決
- 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
PubMed studies (3)L2 · primary research & systematic reviews
Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults: a systematic review and meta-analysis of randomized controlled trials
Finding: No improvement in global symptoms (response 54% prebiotic vs 63% placebo, NS), abdominal pain, bloating or quality of life. Effect on flatulence depended on type/dose: ≤6 g/day improved flatulence (SMD -0.35) and non-inulin fructans improved it (SMD -0.34), but inulin-type fructans WORSENED flatulence (SMD 0.85). Bifidobacteria increased (WMD 1.16 log10 copies).
View on PubMed Efficacy of probiotics, prebiotics and synbiotics in irritable bowel syndrome: a systematic review and meta-analysis of randomized, double-blind, placebo-controlled trials
Finding: Probiotics had a therapeutic role in IBS, but efficacy of prebiotics and synbiotics remained uncertain due to a deficiency of available RCTs. No pooled prebiotic effect estimate could be derived.
View on PubMed Systematic review with meta-analysis: the efficacy of prebiotics, probiotics, synbiotics and antibiotics in irritable bowel syndrome
Finding: Data for prebiotics and synbiotics were sparse and insufficient to draw conclusions. The clearest positive findings were for some probiotic combinations and for the antibiotic rifaximin in non-constipated IBS, not for prebiotics.
View on PubMed Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …
L4a US FDA
Supportive
the FDA intends to exercise enforcement discretion ... for the use of inulin (and inulin-type fructans) ... as a dietary fiber on the Nutrition and Supplement Facts labels source↗
L4b EU EFSA
Supportive
L4c UK NHS
Neutral
Government guidelines say our dietary fibre intake should increase to 30g a day, as part of a healthy balanced diet. source↗
L4d TW TFDA / 衛福部
Neutral
目前健康食品可以宣稱的保健功效項目共有13項，包括調節血脂、胃腸功能改善、護肝、免疫調節、骨質保健、不易形成體脂肪、抗疲勞、輔助調整過敏體質、調節血糖、延緩衰老、牙齒保健、促進鐵吸收、輔助調節血壓。 source↗
L4e WHO
Neutral
WHO recommends an intake of naturally occurring dietary fibre of at least 25 g per day for adults. source↗
L5a NIH Office of Dietary Supplements
Cautious
L5c Cleveland Clinic
Neutral
L5d Harvard Health
Cautious
L5e Specialty Society (condition-mapped)
Against