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In the fertile valleys of East Asia, there’s a plant called konjac, which is part of the Araceae family. It looks like it has a root, but it really grows from a bulb-like part underground. This part contains glucomannan, a type of natural fiber that’s really good for you. People in Asia have been using it for hundreds of years to stay healthy.

Glucomannan: What are the health benefits?
Glucomannan - Shutterstock Images

The konjac plant is used in cooking because it can make foods thicker. It’s used in dishes like shirataki noodles and konjac jelly, mainly in Asian foods. Besides making food, it’s also thought to be good for your health and has been used in traditional medicine for a long time.

Today, glucomannan is popular worldwide as a dietary supplement. People interested in health are using it for its possible benefits in managing weight, controlling blood sugar, and improving digestion.

What is Glucomannan?

Glucomannan is a type of dietary fibre that dissolves easily in water. It is a water-soluble fiber. Glucomannan comes from the roots of the konjac plant. This plant grows in parts of Asia like Japan and Taiwan[1].

The chemical structure of glucomannan is made up of long chains of sugar molecules called mannose and glucose. These chains are linked together to form strands. The strands have the ability to absorb a lot of water and form a thick gel-like substance. This bulky, gel-forming property is what makes glucomannan useful as a dietary fiber supplement[2].

What exactly is the working mechanism of Glucomannan?

As per research, when consumed, glucomannan absorbs water in the stomach, expanding and forming a bulky fibre[3]. This process helps in:

  • Reducing Metabolite Release: Glucomannan slows down how fast certain substances from plant-based foods are released during digestion. This affects how our body processes amino acids, the building blocks of proteins and carbohydrates, our main energy source.
  • Gelation Mechanism: Glucomannan works by soaking up water to form a jelly-like stuff. This process can change how our body digests food and absorbs important nutrients.

Research Supported Health Benefits of Glucomannan

Glucomannan may provide several potential health benefits, particularly in three main areas –

  • Digestive Health: Studies show glucomannan supplements can help relieve constipation by making stools easier to pass. The fiber also feeds the beneficial gut bacteria which aids in overall digestive health[4].
  • How does it work: Glucomannan is a soluble fiber that absorbs water and expands in the intestines. This bulking effect helps to soften stool and promote regular bowel movements. Additionally, our review of GlucoTrim notes that Glucomannan promotes healthy digestion.
  • Blood Sugar Control: For people with diabetes or prediabetes, glucomannan may help control blood sugar levels. Glucomannan has been shown to improve blood sugar control and reduce blood lipid levels in diabetics[5].
  • How does it work: When this soluble fiber expands, it slows the absorption of sugar and carbohydrates from the gut into the bloodstream. This prevents blood sugar spikes after meals.
  • Weight Loss: One of the most popular uses of glucomannan is for weight loss and appetite control. However, it’s important to keep expectations realistic – glucomannan is not a magic pill for weight loss but may provide a modest boost when combined with an overall healthy diet and lifestyle.
  • How does it work: The highly viscous fiber forms a gel that travels slowly through the digestive tract, promoting a feeling of fullness and satiety. This may help reduce calorie intake at subsequent meals[6].

Possible Side Effects

These side effects tend to be mild and often subside as your body adjusts to the increased fiber intake.

  • Glucomannan supplements can cause digestive issues, such as bloating and diarrhea, especially if not taken with enough fluids.
  • There’s a risk of choking if glucomannan is consumed without sufficient water, as it can expand in the throat.
  • It may interfere with the absorption of medications and affect blood sugar levels, requiring cautious use by diabetics.
  • Rarely, it can trigger allergic reactions; start with small doses and consult a doctor if you have medical conditions.


When taking glucomannan or its supplements, it’s important to follow the dosage instructions carefully. Typical dosages range from 1-4 grams per day, often split into 2-3 smaller doses before meals. Higher doses above 5 grams per day are generally not recommended

Always take glucomannan supplements with at least 8 ounces (240 ml) of water or other non-alcoholic beverage. It’s also a good idea to continue drinking plenty of fluids throughout the day when using glucomannan products.

Safety Considerations

  • It’s advisable to start with smaller doses of glucomannan around 1-2 grams and increase gradually while monitoring your tolerance.
  • Those with diabetes or taking medications should consult a doctor before use, as glucomannan can affect nutrient absorption and drug metabolism.
  • Glucomannan is also not recommended for pregnant or breastfeeding women due to lack of safety data.


In summary, glucomannan is a soluble dietary fiber derived from the roots of the konjac plant. It has several potential benefits. Glucomannan works by absorbing water and expanding into a bulky gel that travels slowly through the digestive system. This gel formation can help regulate appetite, making it a key factor in weight management, as discussed in the Clavusin Review.

While evidence looks promising in certain areas, more research is still needed to fully substantiate all of glucomannan’s claimed benefits. It’s important to follow dosage instructions carefully and take glucomannan and its supplements with plenty of fluids to prevent choking or blockages.

Those with medical conditions or taking medications should consult a doctor before using glucomannan supplements.

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6 Sources

We review published medical research in respected scientific journals to arrive at our conclusions about a product or health topic. This ensures the highest standard of scientific accuracy.

[1] Glucomannan :
[2] Konjac :
[3] Review of Konjac Glucomannan Structure, Properties, Gelation Mechanism, and Application in Medical Biology :
[4] Fiber (glucomannan) is beneficial in the treatment of childhood constipation :
[5] Effects of Glucomannan Supplementation on Type II Diabetes Mellitus in Humans: A Meta-Analysis :
[6] The effects of gelled konjac glucomannan fibre on appetite and energy intake in healthy individuals: a randomised cross-over trial :

Jason Vredenburg, RD

Jason Vredenburg is a nutrition writer with over twenty years of experience as a Registered Dietitian. He has researched and written nu