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Gm8.5
Glucomannan Research
Likely helpsModerate safety
39 peer-reviewed studies
What the evidence says
Likely helps
Glucomannan appears to help in 12 of 13 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 2005–2026 with a typical study size of 53 participants.
Based on 39 studies · 9 meta-analyses · 24 RCTs · 9,737 total participants
Confidence
High
What the studies found
12helped1unclear· 26 more without graded effect data
By outcome
Weight managementSatiety and reduced caloric intake · 4-8 weeks
Digestive healthPrebiotic fiber promotes healthy bowel function and microbiome · 1-2 weeks
Likely helps33 studies
Heart & blood pressure
Mostly mechanism / observational3 studies
Therapeutic & clinical
Too few graded studies1 study
By the numbers
Pulled from 34 studies with measurable effects
Likely real effects
100%
across studies
People studied
9,737
typical study: 53 people
Strongest designs
33
9 pooled, 24 randomised
Showed benefit
92%
12/13 studies
How long studies ran
1–4 weeks
3
1–3 months
2
3+ months
2
Populations Studied
Adults4
Adults with obesity2
Healthy adults2
Type 2 diabetes mellitus patients2
Active research area
17 studies in the last 5 years · Latest meta-analysis: 2024
200520152026
1Body weight reductionMeta-AnalysisCited 11×n=6,171 · very large study2023
We conducted random-effects network meta-analysis with a Frequentist framework to estimate mean difference [MD] and 95% confidence interval [CI] of the effect of nutraceuticals on weight loss.
Shahinfar H et al. · Pharmacological research (2023)
Noticeable benefit
← WorseNo effectBetter →
We conducted random-effects network meta-analysis with a Frequentist framework to estimate mean difference [MD] and 95% confidence interval [CI] of the effect of nutraceuticals on weight loss.
Supplementations with green tea (MD: -1.25 kg, 95%CI: -1.68, -0.82) and glucomannan (MD: -1.36 kg, 95%CI: -2.17, -0.54) demonstrated small weight loss, also the certainty of evidence was rated low.
Based on our findings, supplementations with nutraceuticals can result in a small weight loss in adults with overweight or obesity.
2Type II diabetes managementMeta-AnalysisCited 5×n=440 · medium study2023
Our analysis indicates that glucomannan is an effective nutritional intervention for type II diabetes.
Zhang Z et al. · Nutrients (2023)
We searched databases including PubMed, Cochrane, the comprehensive biomedical research database (Embase), Web of Science, and China National Knowledge Infrastructure (CNKI) for literature on glucomannan and type II diabetes.
Six randomized controlled trials (RCTs) were eligible (n = 440 participants) to be included in our analysis.
Our analysis indicates that glucomannan is an effective nutritional intervention for type II diabetes.
Data from 6 trials suggested no impact of KJM on apolipoprotein B.Conclusions: Our findings support the intake of ∼3 g KJM/d for reductions in LDL cholesterol and non-HDL cholesterol of 10% and 7%, respectively.
While some dietary supplements containing isolated organic compounds warrant further investigation to determine efficacy and safety, there is currently insufficient evidence to recommend any of these dietary supplements for weight loss.
Bessell E et al. · International journal of obesity (2005) (2021)
There was no statistically significant effect on weight for fructans compared to placebo (p = 0.24).
While some dietary supplements containing isolated organic compounds warrant further investigation to determine efficacy and safety, there is currently insufficient evidence to recommend any of these dietary supplements for weight loss.
The evidence from available RCTs does not show that glucomannan intake generates statistically significant weight loss.
Onakpoya I et al. · Journal of the American College of Nutrition (2014)
No clear effect
← WorseNo effectBetter →
A meta-analysis (random effect model) of 8 RCTs revealed a nonstatistically significant difference in weight loss between glucomannan and placebo (mean difference [MD]: -0.22 kg; 95% confidence interval [CI], -0.62, 0.19; I(2) = 65%).
The evidence from available RCTs does not show that glucomannan intake generates statistically significant weight loss.
Future trials should be more rigorous and better reported.
11Weight management and metabolic indicatorsSystematic Review2026
This review emphasized the need for purpose-driven supplement selection that integrates efficacy, safety, usage context, and evidence level, and the importance of consumers' critical information appraisal capacity, supported by structured information provision and education.
Lee H et al. · Nutrients (2026)
PubMed, MEDLINE, and Google Scholar databases were searched for studies published between 1 January 2020 and 10 October 2025.
Although some studies have reported improvements in weight and metabolic indicators, consistent scientific evidence has not yet been established.
This review emphasized the need for purpose-driven supplement selection that integrates efficacy, safety, usage context, and evidence level, and the importance of consumers' critical information appraisal capacity, supported by structured information provision and education.
13Body weight reductionRCTCited 10×n=112 · medium study2024
Dietary supplementation with glucomannan, inulin, and psyllium effectively promotes weight loss and improves body composition in individuals with obesity, particularly those with specific genetic polymorphisms.
Pokushalov E et al. · Nutrients (2024)
Barely noticeable benefit
← WorseNo effectBetter →
Likely real
The experimental group showed significant reductions in body weight (treatment difference: -4.9%; 95% CI: -6.9% to -2.9%; p < 0.01) and BMI (treatment difference: -1.4 kg/m2; 95% CI: -1.7 to -1.2; p < 0.01) compared to placebo.
Further significant decreases in fat mass (treatment difference: -13.0%; 95% CI: -14.4 to -11.7; p < 0.01) and visceral fat rating (treatment difference: -1.3; 95% CI: -1.6 to -1.0; p < 0.01) were noted.
Homozygous minor allele carriers experienced greater decreases in body weight (treatment difference: -3.2%; 95% CI: -4.9% to -1.6%; p < 0.01) and BMI (treatment difference: -1.2 kg/m2; 95% CI: -2.0 to -0.4; p < 0.01) compared to heterozygous allele carriers.
This study suggests that manipulating the human gut microbiome through dietary interventions could be a promising therapeutic approach to managing prediabetes and preventing or delaying diabetes.
Beteri B et al. · Nutrients (2024)
The intervention group showed a significant increase in alpha diversity and butyrate-producing bacteria, with reductions in HbA1c and FPG levels below prediabetes thresholds.
Measurements included gut microbiota composition, glycated haemoglobin (HbA1c), fasting plasma glucose (FPG), plasma lipids, anthropometry, body composition, blood pressure, and dietary intake.
No significant changes were observed in the placebo group.
15Gastrointestinal symptoms in functional constipationRCTCited 1×n=66 · small study2025
Konjac glucomannan significantly ameliorated gastrointestinal symptoms in elite athletes with functional constipation, potentially via modulation of the gut microbiota.
Zhu Y et al. · European journal of nutrition (2025)
Compared to the placebo group, the KGM group exhibited significant improvements in PAC-SYM, PAC-QoL, BMF, and BFI scores (p < 0.05 for all).
Konjac glucomannan significantly ameliorated gastrointestinal symptoms in elite athletes with functional constipation, potentially via modulation of the gut microbiota.
16Glycaemic response and satiationCrossoverCited 1×n=16 · very small study2025
These novel findings suggest that SB can modulate insulin response and influence appetite regulation, highlighting its potential use in weight management strategies.
Ancu O et al. · European journal of nutrition (2025)
SBD intake significantly reduced the insulin concentration compared to dextrose alone at 45, 75, and 90 min post-intake.
These novel findings suggest that SB can modulate insulin response and influence appetite regulation, highlighting its potential use in weight management strategies.
17Metabolic syndrome managementRCTCited 6×n=58 · small study2024
Our study shows that the food supplement tested is a valid and safe alternative therapeutic approach in the management of MetS and all its resulting risk factors, as its efficacy has been demonstrated across anthropometric, glucose, lipid and hepatic parameters.
Citarrella R et al. · Nutrients (2024)
Fifty-eight subjects with MetS and T2DM or impaired glucose tolerance assuming metformin, were randomly assigned to take a food supplement of glucomannan, D-chiro-inositol, Cinnamomum zeylanicum blume and inulin at a daily fixed dose of 4 g orally for four months.
Body weight, waist circumference, plasma lipid profile (total cholesterol, LDL, HDL and triglyc-erides), plasma glycaemic profile and visceral adiposity index (VAI) were measured at baseline and after four months of supplementation.
Our study shows that the food supplement tested is a valid and safe alternative therapeutic approach in the management of MetS and all its resulting risk factors, as its efficacy has been demonstrated across anthropometric, glucose, lipid and hepatic parameters.
18Hunger intensity and waist circumference reductionRCTCited 5×n=42 · small study2023
Forty-two participants aged 18 to 45 years completed our randomized, double-blind, placebo-controlled clinical trial.
Fernandes ACS et al. · International journal of biological macromolecules (2023)
Forty-two participants aged 18 to 45 years completed our randomized, double-blind, placebo-controlled clinical trial.
Participants were randomly assigned to consume for fourteen days, 2 candies per day, containing 250 mg of KGM or identical-looking placebo candy with 250 mg of flaxseed meal, shortly after breakfast and dinner.
Glucomannan supplements administered over 8 weeks were well tolerated but did not promote weight loss or significantly alter body composition, hunger/fullness, or lipid and glucose parameters.
Keithley JK et al. · Journal of obesity (2013)
Glucomannan supplements administered over 8 weeks were well tolerated but did not promote weight loss or significantly alter body composition, hunger/fullness, or lipid and glucose parameters.