Glucomannan / Konjac Glucomannan (KGM) for Constipation
Verdict: Published with Warning
Across 4 PubMed studies, the evidence for Glucomannan / Konjac Glucomannan (KGM) in Constipation grades Tier C — weak evidence. Effective, but with safety or population caveats.
C 🟠 C Weak Evidence Published with Warning
Why this grade7-layer evidence engine
⚖️
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditableRaw score 0.61
D
C
B
A
S
← counter-evidence / ineffectiveeffective / strong evidence →
Final grade
C · Published with Warning
Confidence
74%
Broadly consistent
Evidence level
E3
Single high-quality meta-analysis
▸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 = 0.61
- 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 1 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status
PubMed studies (4)L2 · primary research & systematic reviews
Effect of glucomannan on functional constipation in children: a systematic review and meta-analysis of RCTs
Finding: Glucomannan increased defecation frequency (MD=1.40, 95% CI 0.36-2.44, p=0.008) but no significant effect on stool consistency (SMD=0.48, p=0.300) or treatment success rate (RR=1.36, p=0.110).
View on PubMed Effects of konjac glucomannan on GI symptoms and gut microbiota in athletes with functional constipation: double-blind RCT
Finding: Konjac glucomannan group showed significant improvements in PAC-SYM, PAC-QoL, BMF, and BFI vs placebo (p<0.05 all); increased microbial alpha-diversity and beneficial bacteria.
View on PubMed Supplementation of konjac glucomannan into low-fiber Chinese diet promoted bowel movement and improved colonic ecology in constipated adults
Finding: Weekly defecation frequency increased from 4.1±0.6 to 5.3±0.6 (~30% improvement); increased lactobacilli/bifidobacteria, SCFAs, lower fecal pH.
View on PubMed Glucomannan is not effective for the treatment of functional constipation in children: double-blind, placebo-controlled RCT
Finding: No significant difference in treatment success vs placebo (RR 0.95, 95% CI 0.6-1.4); stool consistency improved at week 1 (p<0.0001) but worsened at week 3 (p=0.008); abdominal pain increased in glucomannan group (p=0.04 and p<0.0001).
View on PubMed Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …
L4a US FDA
Cautious
These small cup-like products maintain their characteristics (i.e., shape, texture, firmness) and do not melt when placed in the mouth. An FDA Health Hazard Evaluation Board and physiologists with the Consumer Products Safety Commission (CPSC) assessed the products and concluded that the physical characteristics of the small cup-like candies (particularly, the packaging, shape, slipperiness, an… source↗
L4b EU EFSA
Supportive
L4d TW TFDA / 衛福部
Cautious
市售含蒟蒻成分果凍應於個別產品外包裝顯著標示警語：1.請勿以強吸一口整粒吞食。2.五歲以下幼兒請勿食用。3.老人及兒童食用時，請大人陪伴以匙分段進食。4.請細嚼慢嚥，以免噎到。5.嬉戲時請勿食用。6.請咀嚼，勿整粒吞食（擇一標示）。適用範圍包含剖面直徑4.5公分（含）以內球形或類似球形產品，及非球形直徑3.1公分（含）以內、入口後產品表面平順滑溜之果凍。自民國95年1月1日起實施（衛署食字第0940405150號，94年9月30日公告）。 source↗
L4e WHO
Neutral
The Committee concluded that the additional studies provided no evidence of adverse effects attributable to konjac flour in experimental animals. Metabolically, konjac flour behaves in the intestine in a similar way to other polysaccharide gums. ADI 'not specified' for konjac flour. source↗
L5a NIH Office of Dietary Supplements
Cautious
L5c Cleveland Clinic
Supportive
Konjac glucomannan fiber helps firm up poop. Because soft, bulky stools are easier to pass, you're less likely to become constipated and develop hemorrhoids. source↗