Organic Konjac - Targeted on "appetite suppressant" effects

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

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

✔ Weight loss and appetite regulation

- Studies on appetite: 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).
The results: The 50% and 100% konjac meals resulted in asharp reduction in energy intakein the following meal (–23% and –47% of energy consumed) compared to the control mealpubmed.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 foundno significant weight losswith glucomannan (mean difference ~–0.22 kg, p>0.05 vs placebo)pubmed.ncbi.nlm.nih.govThe authors conclude that the available evidence does not support a weight-loss action.

-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 appetitepubmed.ncbi.nlm.nih.gov. Satiety, body composition and metabolism (lipids, glucose) parameters 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,clinical evidence is neutral or negativeon weight loss itself: meta-analyses and randomized trials shownonesignificant weight loss with glucomannanpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov.

Only controlled dietary studies indicate adecrease in calorie intakevia greater satietypubmed.ncbi.nlm.nih.gov.

✔ Cholesterol and triglycerides

-Reduction of LDL cholesterol: 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 of 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 decreasesignificanttotal 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 about –0.3 mmol/L (p<0.01); triglyceride, on the other hand, was not reliably changed (no statistical differences)bmccardiovascdisord.biomedcentral.comThese results confirm a positive lipid effect of KGM.

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

-Triglycerides: Most studies did not find a marked effect on triglycerides. For example, the 2024 meta-analysis notes that TGs remain unchanged (p≈0.79)bmccardiovascdisord.biomedcentral.com.
Generally speaking, the main benefit lies on LDL-cholesterol (and total cholesterol), withneutral effect on triglycerides.

✔ Blood sugar (diabetes and carbohydrate metabolism)

-Fasting blood sugar: 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 averagepubmed.ncbi.nlm.nih.govThis modest effect is statistically significant but clinically mild.

- Postprandial blood sugar: In the same meta-analysis, postprandial blood glucose (2h after loading) 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) reports significant decreases in both fasting and postprandial glucose, as well as a decrease in fasting insulin.mdpi.comThe contradiction may be explained by the fact that the included studies differ (healthy subjects vs. diabetics).

- Conclusion: Overall, the addition of glucomannan shows aslight improvementglycemic control, especially fasting blood sugarpubmed.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 KGMpubmed.ncbi.nlm.nih.gov.
In summary, glucomannan acts as a mild laxative, making stools easier to pass.

Conclusion: Glucomannan isuseful for relieving constipation: it significantly increases the frequency of stools and improves their consistencypubmed.ncbi.nlm.nih.govpubmed.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. One study in adults showed that 4.5 g/d of KGMincrease significantlythe fecal concentration oflactobacilliand 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 the concentrations of acetate, propionate and butyrate in the stool 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 phasepubmed.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 gut health beyond its laxative effect. It enriches “friendly” gut bacteria, increases SCFA production, and lowers colonic pH.pubmed.ncbi.nlm.nih.govThese effects probably contribute to its benefits on transit and perhaps on overall metabolism (cholesterol, blood sugar).

General conclusion

Clinical studies show that konjac glucomannan iseffective in terms of appetite lossbutlittle active to induce weight loss(neutral effects on body weight in the vast majority of trialspubmed.ncbi.nlm.nih.gov).

He haspositive effects on lipid balance(moderate reduction in LDL-cholesterol and total cholesterol with ~3–5 g/d)nutraingredients-usa.combmccardiovascdisord.biomedcentral.com, as well as on thefasting blood sugar(slight reduction, eg –0.6 mmol/L)pubmed.ncbi.nlm.nih.gov.

THEtriglyceride profileremains generally unchanged. Digestively, glucomannan increases stool frequency and volume and relieves constipationpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov, while promoting a microbiota rich in bifidobacteria and lactobacillipubmed.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/day) and the profile of the subjects (e.g. obese vs. diabetic)nutraingredients-usa.compubmed.ncbi.nlm.nih.gov. The results are overallpositive on loss of appetite, LDL cholesterolAndtransit,modest on blood sugar, Andpoor on weight loss(neutral)pubmed.ncbi.nlm.nih.govnutraingredients-usa.comThese conclusions are supported by available meta-analyses and RCTs.

Sources:Meta-analyses and RCTs mentioned above (PubMed/DOI)pubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govnutraingredients-usa.combmccardiovascdisord.biomedcentral.compubmed.ncbi.nlm.nih.govmdpi.compubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov

Extracted from the root of the konjac plant, glucomannan is one of the richest natural sources of dietary fiber.

It has an exceptional ability to absorb water, so much so that if you empty the contents of one capsule into a small glass of water, all the liquid turns into jelly.

These particular characteristics actively contribute to weight loss.

Konjac is a plant whose root contains a very special soluble fiber calledglucomannanThis fiber has several interesting links with the intestinal microbiota:

1. Prebiotic property:
   Glucomannan is not digested in the stomach or small intestine. It therefore reaches the colon intact, where it serves as food for beneficial bacteria. By promoting the growth of these microorganisms (such as Lactobacillus and Bifidobacterium), it helps maintain or restore a healthy microbiota balance.
   
2. Production of short-chain fatty acids (SCFAs):
   Glucomannan fermentation by the microbiota leads to the production of SCFAs (including butyrate, acetate, and propionate). These compounds play a crucial role in:

Maintaining the health of the intestinal wall,
Regulation of intestinal transit,
Influence on metabolism and the immune system.

3. Effects on metabolic health:
Through these actions, konjac may indirectly help improve various aspects of health, such as cholesterol management, blood sugar regulation, and the prevention of certain inflammations, partly through its impact on the microbiota.

In summary, the link between konjac and the microbiota is primarily due to glucomannan's ability to act as a prebiotic. By feeding beneficial bacteria and stimulating the production of SCFAs, it contributes to the positive modulation of the gut microbiota, which can have beneficial effects on digestive and metabolic health.