Glucomannan

Glucomannan is a type of fiber that is often used in many Asian health foods. It is also used in many weight loss pills. There is some evidence that glucomannan may be effective for type 2 diabetes, and preliminary studies suggest that it may help with constipation, high cholesterol, and obesity as well. Possible side effects include digestive symptoms (such as bloating and gas).

 

What Is Glucomannan?

Glucomannan is a type of vegetable fiber that comes from the root of a plant known as konjac (Amorphophallus konjac, to be specific). This fiber is commonly used in Asian health foods, and many herbal supplements now contain glucomannan. In addition to its use in foods, the fiber is often used for the following purposes:
 
(Click Glucomannan Uses for more information on what it is used for.)
 

Which Products Contain Glucomannan?

Currently there are a large number of products that contain glucomannan. It can be purchased in capsules, tablets, powders, shakes, and a variety of food products (such as konjac noodles or glucomannan flour). Many popular weight loss pills contain it (in combination with other ingredients), including:
 

How Does It Work?

Glucomannan works like any other fiber product to relieve constipation and lower cholesterol, as well as to help with obesity and type 2 diabetes. It is a fiber that is not absorbed into the body (it stays in the digestive tract). It increases the water absorption into the stool in the colon, helping to relieve constipation. It probably works to lower cholesterol by helping the body get rid of cholesterol through the stool. Because fiber slows the emptying of the stomach, it can help people feel full and can help keep blood sugar more even. This is probably how glucomannan fiber helps with obesity and type 2 diabetes.
 

Is It Effective?

There is actually some evidence that the substance may be effective for type 2 diabetes, and preliminary studies suggest that it may help with constipation, high cholesterol, and obesity as well.
 
(Click Does Glucomannan Work? for more information. You can also click How To Lose Weight to find helpful suggestions for losing weight.)
 

Dosing Information

As with any other fiber, a large quantity of glucomannan is usually necessary in order to produce the desired effects. The recommended dose will vary depending on the particular product and the condition being treated.
 
(Click Glucomannan Dosage for more information.)
 

Side Effects of Glucomannan

As with any fiber product, glucomannan may cause certain digestive symptoms (such as bloating or gas). There have also been reports of the tablets getting stuck in the throat.
 
(Click Glucomannan Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
 

Drug Interactions

Glucomannan may interact with a number of other medications or supplements (see Glucomannan Drug Interactions).
 

Is It Safe?

It appears to be safe in many situations. However, some people may be more likely to experience problems due to glucomannan. Therefore, you should talk with your healthcare provider before taking it if you have:
 
  • A narrowing (stricture) of the esophagus
  • Difficulty swallowing
  • Diabetes
  • Any other chronic disease or health problem.
     
Also, let your healthcare provider know if you are:
 
Make sure to tell your healthcare provider about any other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Glucomannan Safety for more information, including any available warnings and precautions.)
 

What If I Take an Overdose?

It is not known what exactly to expect from a glucomannan overdose. If you think you may have taken too much, seek immediate medical attention.
 
(Click Glucomannan Overdose for more information.)
 

Storage Methods for Glucomannan

Refer to the label of your individual glucomannan product for information on how best to store it. Keep glucomannan and all other medications or supplements out of the reach of children.
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;