Summary of results

• THE glucomannan increases satiety And reduces appetite significantly.
• He lowers LDL and total cholesterol , and slightly improves fasting blood sugar .
• He is effective against constipation , by increasing the frequency and quality of stools.
• He favorably modifies the microbiota , in particular by enriching the bifidobacteria
• It promotes the production of short-chain fatty acids (SCFAs) , which are beneficial for intestinal health.

Clinical efficacy of the “Organic Konjac” formula

Konjac (Amorphophallus konjac) and glucomannan: review of human clinical trials

Konjac glucomannan is a highly viscous soluble fiber studied for its effects on weight, lipids, and blood sugar, as well as on intestinal transit and the microbiota. Below, we summarize the main clinical trials by area:

✔ Weight loss and appetite regulation

- Appetite studies : In a crossover study in 16 healthy subjects, Au-Yeung et al. (2018) replaced part of a high-starch meal with very high konjac noodles (0%, 50%, or 100% glucomannan).
Results: The 50% and 100% konjac meals resulted in a significant reduction in energy intake in the following meal (–23% and –47% energy consumed) compared to the control meal pubmed.ncbi.nlm.nih.gov .
This indicates that konjac fiber can increase satiety and decrease appetite.
(Note: Hunger/fullness sensations were paradoxically lower for the 100% KGM meal, but total consumption was significantly lower.)

- Meta-analyses (adults) : Onakpoya et al. (2014) analyzed 8 trials (≈418 subjects) and found no significant weight loss with glucomannan (mean difference ~–0.22 kg, p>0.05 vs. placebo) pubmed.ncbi.nlm.nih.gov . The authors conclude that the available evidence does not support a weight-loss effect.

- Randomized trials (adults) : For example, Keithley et al. (2013) subjected 53 adults (BMI 25–35) to 8 weeks of glucomannan (1.33 g before each meal, ≈4 g/d) or placebo. The result: no difference in weight loss (–0.40 kg vs. –0.43 kg) or change in appetite pubmed.ncbi.nlm.nih.gov . Parameters of satiety, body composition, and metabolism (lipids, glucose) remained comparable to controls.

- Children and adolescents : A trial in 96 obese children/adolescents (3 g/d for 12 weeks, identical dietary advice) showed no effect on BMI or weight loss (BMI z-score change ~0 in both groups) pubmed.ncbi.nlm.nih.gov .

Conclusion : Overall, the clinical evidence is neutral or negative on weight loss per se: meta-analyses and randomized trials show no significant weight loss with glucomannan pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov .

Only controlled dietary studies indicate a decrease in caloric intake via greater satiety pubmed.ncbi.nlm.nih.gov .

✔ Cholesterol and triglycerides

- LDL-cholesterol reduction : A meta-analysis by Hoang et al. (2017) (12 trials, adults) shows that on average 3 g/d of glucomannan reduces LDL-cholesterol by approximately –0.35 mmol/L (–10%) and non-HDL cholesterol by approximately –0.32 mmol/L (–7%) nutraingredients-usa.com .
This study concludes that ~3 g/d is sufficient for these significant reductions in LDL.

- Total cholesterol : In a recent systematic review (2024) of 14 RCTs, glucomannan supplementation induced a significant decrease in total cholesterol (SMD –3.30, p<0.001) and LDL (SMD –2.99, p≈0.006) bmccardiovascdisord.biomedcentral.com .
For example, the study found a mean reduction in LDL of approximately –0.3 mmol/L (p<0.01); triglyceride, on the other hand, was not reliably changed (no statistical differences) bmccardiovascdisord.biomedcentral.com . These results confirm a positive lipid effect of KGM.

- Clinical trials (children) : The Zalewski (2019) trial in children reported a modest reduction in total and LDL cholesterol in the KGM group (3 g/d) compared to placebo after 12 weeks pubmed.ncbi.nlm.nih.gov . Thus, even in obese children, glucomannan tends to improve the lipid profile.

- Triglycerides : Most studies have not found a marked effect on triglycerides. For example, the 2024 meta-analysis notes that TGs remain unchanged (p≈0.79) bmccardiovascdisord.biomedcentral.com .
Overall, the main benefit is on LDL-cholesterol (and total cholesterol), with a neutral effect on triglycerides .

✔ Blood sugar (diabetes and carbohydrate metabolism)

- Fasting blood glucose : Mirzababaei et al. (2022) analyzed 6 trials (124 subjects) and found that glucomannan slightly reduced fasting blood glucose by –0.60 mmol/L (p=0.03) on average pubmed.ncbi.nlm.nih.gov . This modest effect is statistically significant but clinically mild.

- Postprandial glycemia : In the same meta-analysis, postprandial glycemia (2h after load) was not significantly lowered (WMD≈–2.07 mmol/L, p=0.18) pubmed.ncbi.nlm.nih.gov .
In contrast, a recent meta-analysis in type 2 diabetics (Zhang 2023) reported significant decreases in both fasting and postprandial glucose, as well as a decrease in fasting insulin mdpi.com . The contradiction may be explained by the fact that the included studies differ (healthy subjects vs. diabetics).

- Conclusion : Overall, the addition of glucomannan shows a slight improvement in glycemic control, especially on fasting blood glucose pubmed.ncbi.nlm.nih.gov .
The effect on postprandial glycemia is less clear. These results suggest a modest benefit for glycemic regulation, complementary to its lipid-lowering effect.

✔ Intestinal transit and constipation : All trials report an increase in stool frequency under glucomannan.
For example, Chen et al. (2006) observed in healthy adults (4.5 g/d KGM) an increase in daily defecation of approximately +27% (p<0.05) pubmed.ncbi.nlm.nih.gov .
In children with brain damage (chronic constipation), Staiano et al. (2000) also noted a significant increase in stool frequency with KGM (p<0.01) pubmed.ncbi.nlm.nih.gov .


- Consistency and comfort : In Staiano's pediatric study, glucomannan also improved fecal consistency (clinical score) and reduced episodes of painful defecation (p<0.01) pubmed.ncbi.nlm.nih.gov .
Similarly, constipated patients decreased their use of laxatives/suppositories with KGM pubmed.ncbi.nlm.nih.gov .
In summary, glucomannan acts as a mild laxative, making stools easier to pass.

Conclusion : Glucomannan is useful in relieving constipation : it significantly increases stool frequency and improves stool consistency pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov .
In practice, trials typically recommend 3–6 g/d (divided with meals) to observe these effects.

✔ Other potential effects (microbiota, digestive health)

- Prebiotic effect : As a fermentable fiber, glucomannan promotes the growth of beneficial bacteria. A study in adults showed that 4.5 g/d of KGM significantly increased the fecal concentration of lactobacilli and the total number of beneficial bacteria (bifidobacteria, lactobacilli) pubmed.ncbi.nlm.nih.gov .
Similarly, supplementation increased daily production of bifidobacteria and lactobacilli.

- Short-chain fatty acids (SCFAs) : This fermentation produces SCFAs. Under KGM, a decrease in colonic pH and an increase in stool concentrations of acetate, propionate, and butyrate are observed pubmed.ncbi.nlm.nih.gov . For example, Chen (2006) reports a marked increase in fecal SCFAs (acetate, propionate, i-butyrate) during the glucomannan phase pubmed.ncbi.nlm.nih.gov .

- Other observations : Some studies also suggest an indirect effect on hormonal appetite (via GLP-1), but clinical data are limited. The digestive benefits of konjac seem mainly linked to its fibrous action: increase in fecal bolus and modulation of the intestinal microbiota.

Conclusion : Konjac/glucomannan improves intestinal health beyond its laxative effect. It enriches “friendly” intestinal bacteria, increases SCFA production, and lowers colonic pH pubmed.ncbi.nlm.nih.gov . These effects likely contribute to its benefits on transit and perhaps overall metabolism (cholesterol, blood sugar).

General conclusion

Clinical studies show that konjac glucomannan is effective in reducing appetite but not very active in inducing weight loss (neutral effects on body weight in the vast majority of trials pubmed.ncbi.nlm.nih.gov ).

It has positive effects on lipid balance (moderate reduction of LDL-cholesterol and total cholesterol with ~3–5 g/d) nutraingredients-usa.com bmccardiovascdisord.biomedcentral.com , as well as on fasting blood glucose (slight reduction, eg –0.6 mmol/L) pubmed.ncbi.nlm.nih.gov .

The triglyceride profile generally remains unchanged. On the digestive level, glucomannan increases stool frequency and volume and relieves constipation pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov , while promoting a microbiota rich in bifidobacteria and lactobacilli pubmed.ncbi.nlm.nih.gov .

In summary, konjac (glucomannan) is clinically effective in improving certain metabolic parameters (notably cholesterol) and intestinal function, but it is not a "miracle" slimming agent.
Its observed beneficial effects depend on the dosage (often ~3–6 g/d) and the profile of the subjects (e.g., obese vs. diabetic) nutraingredients-usa.com pubmed.ncbi.nlm.nih.gov . The results are generally positive on loss of appetite, LDL cholesterol and transit , modest on blood sugar , and poor on weight loss (neutral) pubmed.ncbi.nlm.nih.gov nutraingredients-usa.com . These conclusions are supported by the available meta-analyses and RCTs.

Sources: Meta-analyses and RCTs mentioned above (PubMed/DOI) pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov nutraingredients-usa.com bmccardiovascdisord.biomedcentral.com pubmed.ncbi.nlm.nih.gov mdpi.com pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov