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What You Should Know About Glucomannan Supplements

Story at-a-glance

  • A natural, water-soluble dietary fiber that comes from the konjac root, glucomannan is a supplement considered to be a “bulk-forming” laxative
  • What sets glucomannan apart from other types of soluble fiber is its high viscosity – it’s actually one of the most viscous dietary fibers available today
  • Aside from being used to make shirataki noodles, konjac root can also be made into a gel that is cut up and served with a sauce for dipping

With the increasing rates of obesity and obesity-related diseases today, many people are now looking for effective methods to help shed their excess weight and get the physique they desire. But beware: Many of the weight loss supplements available today are nothing more than marketing fads that rip off unsuspecting consumers.

However, there are certain supplements that may potentially aid in managing your weight. One example is glucomannan. But does it really work? Here’s what you should know about this product.

What Is Glucomannan?

A natural, water-soluble dietary fiber that comes from the konjac root, glucomannan is a supplement considered to be a “bulk-forming” laxative.1 For the record, it is not a weight loss pill2 – rather, this form of fiber works by absorbing water in the stomach and giving a feeling of fullness.3 It also promotes a larger, bulkier stool that can easily pass through the colon without much pressure and does not require excessive straining to be expelled.4

What sets glucomannan apart from other types of soluble fiber is its high viscosity – it’s actually one of the most viscous dietary fibers available today. In fact, if you empty a glucomannan capsule in a small glass of water, it will turn into gel.5 Other mechanisms of action that may contribute to glucomannan’s potential effects include:

Glucomannan is available in supplement form, as a powder or capsule. It may be added to pasta and flour as well, as is actually the main ingredient in shirataki noodles.10 Because glucomannan has no smell or taste, it can be mixed into any food or drink. However, take note that it will cause any food or liquid to thicken.11

The Konjac Root: The Main Source of Glucomannan

As mentioned above, glucomannan comes from the konjac root (Amorphophallus konjac),12 and comprises 40 percent of its dry weight.13 Also known as elephant yam, this plant is popular in East Asia, and has long been used in countries like Japan and China as a food and traditional medicine.

Aside from being used to make shirataki noodles, konjac root can also be made into a gel that is cut up and served with a sauce for dipping. It’s valued for its gelatinous texture and not its taste – in fact, konjac root takes on the taste of whatever it’s dipped or marinated in or cooked with.

Glucomannan supplements are not the only thing konjac root is used for, though. It’s also used to manufacture powder, flour and candies.14

What Do the Studies Say About Glucomannan?

There have been several studies conducted on glucomannan and its potential to help with weight loss. However, the results are unfortunately conflicting. For example, a 2005 study, which included 176 healthy overweight people on a calorie-controlled diet, found that those who were given glucomannan had significant weight reduction as opposed to those who were only given a placebo.15

Recent studies have contradicted these findings, though. In 2013, a study published in the Journal of Obesity compared glucomannan to a placebo, with 53 participants taking either of the two before their meals. After eight weeks, no significant changes in body weight, hunger, body fat, blood sugar levels or blood cholesterol was noted.16 A 2014 analysis, which reviewed and combined data from eight small studies on this supplement’s effect on obese and overweight people, found no significant weight loss effects.17

However, in 2015, a study tested glucomannan versus a placebo on 83 individuals for two months and found that although there are no overall benefits, the researchers noted significant reductions in body fat, body weight and LDL cholesterol – but only among participants who were compliant with their protocol.18 Hence, the weight loss effects of this supplement are still inconclusive.

Taking Glucomannan May Also Lead to Side Effects

Because it is a type of fiber, glucomannan may cause mild but unpleasant effects like gas, bloating, diarrhea or soft stools after introducing this supplement to their diet. This is because of the sudden introduction of high amounts of fiber into a low-fiber diet. These effects are said to disappear after a few weeks, though.19

People who are taking certain medications should also be wary of taking glucomannan supplements. For example, it’s been known to reduce the absorption of the diabetes drug sulfonylurea. If you are taking any type of medication, consult your physician before taking glucomannan.

Note: Do Not Rely on Glucomannan to Achieve Your Optimal Weight

While high-fiber supplements may provide some benefits to your health, remember that they are not the end-all solution to optimal weight management. It’s true that, if obtained from the best sources, fiber can definitely boost your health. However, other aspects of your lifestyle must also be addressed, such as exercise and a healthy diet, to fully reap the benefits.

In addition, glucomannan is not the only fiber source that you should rely on. Ideally, you should get this from foods like fresh whole vegetables. Another valuable source is whole husk psyllium. However, make sure that you only take 100 percent organic psyllium husk, as conventional psyllium is a heavily sprayed crop.

Frequently Asked Questions (FAQs) About Glucomannan

Q: Does glucomannan work?

A: The studies of the effectiveness of glucomannan have been inconclusive, with some claiming that it can lead to weight loss, while others saying that it is no better than a placebo.

Q: Is glucomannan safe?

A: Glucomannan is believed to be safe, as long as taken in proper dosages. However, side effects like bloating, flatulence and diarrhea may still occur, especially in people who are used to consuming a low-fiber diet.

Q: Where can I buy glucomannan?

A: You can buy glucomannan online. Some health stores may also carry this type of fiber supplement.

Q: What is glucomannan good for?

A: It’s said that glucomannan may help with weight management. It works by absorbing water in the stomach and giving a feeling of fullness, and also allowing the formation of larger stools.

Q: How much glucomannan should I take?

A: The recommended dosage is anywhere between 1 to 4 grams. Consult your doctor to confirm the ideal dose for you, or if this supplement is advisable for you at all.

Sources and References

  • 1, 4, 12 University of Michigan, Glucomannan
  • 2 Self, Glucomannan: The Weight-Loss Supplement Dr. Oz Loves, July 25, 2011
  • 3 The Journal of Nutrition, Volume 130, Issue 2, 1 February 2000, Pages 272S–275S
  • 5 Express, July 30, 2018
  • 6 Nutr Rev. 2001 May;59(5):129-39.
  • 7 J Nutr. 1997 Apr;127(4):579-86.
  • 8 J Clin Gastroenterol. 2006 Mar;40(3):235-43.
  • 9 Diabetes. 2009 Jul; 58(7): 1509–1517.
  • 10 Therapeutic Use of Medicinal Plants and their Extracts: Volume 2: Phytochemistry and Bioactive Compounds, 2018
  • 11 Livestrong, Glucomannan to Lose Weight, July 18, 2017
  • 13 Understanding Food: Principles and Preparation, 2018
  • 14 Precision Nutrition, All About Glucomannan
  • 15 Med Sci Monit. 2005 Jan;11(1):PI5-8.
  • 16 J Obes. 2013; 2013: 610908.
  • 17 J Am Coll Nutr. 2014;33(1):70-8.
  • 18 J Am Coll Nutr. 2015 Oct 22:1-7.
  • 19 WebMD, Glucomannan: Fat-Fighting Fiber or Fraudulent Fad?, June 4, 2012
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