The Health Benefits of Glucomannan

How glucomannan impact weight loss, blood sugar, and cholesterol

Shirataki noodles, peas, asparagus, star-shaped tofu
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Glucomannan is an extract of konjac (Amorphophallus konjac) and is a source of water-absorbing beta-glucan, a type of soluble fiber. Soluble fiber helps regulate digestion speed, regulate blood sugar, and increase nutrient absorption. While glucomannan is high in dietary fiber, it is very low in calories and contains almost no proteins or vitamins.

Glucomannan is used as a dietary supplement and food in the form of konjac jelly, noodles, and tofu.  It has been studied extensively for its potential effects on body weight, blood glucose, cholesterol, triglycerides, and blood pressure. Additional research has been done on other benefits, such as its potential as an anti-diabetic, anti-obesity, laxative, prebiotic, and anti-inflammatory supplement.

Although glucomannan has been studied for many potential benefits, not all research has shown its effectiveness. More research is necessary to make further conclusions.

Glucomannan and Its Benefits

Glucomannan, the water-soluble dietary fiber supplement from the konjac plant, may help with keeping bowels regular, controlling body weight, and reducing blood cholesterol and blood sugar. The health benefits of glucomannan have been studied extensively and generally considered safe when taken as directed. Here we explore the potential health benefits of glucomannan based on research.

May Help With Weight Management

As a potential weight loss aid, glucomannan has the ability to create bulk that, in turn, produces sensations of fullness. These feelings of fullness then can lead to a reduced calorie intake. It also is a source of soluble fiber that slows the absorption of sugar and cholesterol, and aids in digestion.

To accomplish this, glucomannan forms a protective film on the bowel wall which lengthens the time food remains in the stomach, increases feelings of fullness, and reduces hunger. It also is low in calories, making it a potentially effective weight loss aid.

The studies on using glucomannan for weight loss purposes are mixed. Some research has shown that supplementing with glucomannan may reduce body weight but not body mass index (BMI) in the short term in otherwise healthy adults with overweight or obesity.

Body Mass Index (BMI) is a dated, biased measure that doesn’t account for several factors, such as body composition, ethnic descent, race, gender, and age.

Despite being a flawed measure, BMI is widely used today in the medical community because it is an inexpensive and quick method for analyzing potential health status and outcomes.

Other research showed that daily 4-gram doses of glucomannan consumed over 8 weeks did not lead to weight loss or changes in body composition, feelings of hunger or meal satiation, or impact cholesterol or blood sugar levels.

Meanwhile, another study looked at the effects of glucomannan noodles used as a replacement for carbohydrate-rich versions and found those consuming the glucomannan noodles reduced their calorie and carb intake significantly without leading to consumption of additional calories later. Researchers believe that using glucomannan foods is an effective way to help create a caloric deficit needed for weight loss.

Sources of Soluble Fiber

May Reduce Cholesterol and Blood Sugar

Glucomannan forms a layer around food, inhibiting the absorption of cholesterol and bile acid. Because glucomannan causes slower stomach emptying and delays glucose circulation in the intestines, soluble dietary fibers, including glucomannan, have beneficial effects on blood sugar levels.

Using glucomannan as a supplement has been shown to reduce blood glucose and cholesterol levels in healthy individuals as well as those with diabetes. This reduction is due to the slowed stomach emptying leading to higher absorption rates of nutrients by the small intestine, increasing insulin sensitivity. Slower absorption of sugars means lower blood sugar elevation, an essential factor in controlling diabetes.

May Relieve Constipation

Soluble fiber such as that found in glucomannan improves digestion. The recommended total intake of dietary fiber is around 25 to 30 grams per day with 6 to 8 grams from soluble fiber.

Glucomannan is an excellent source of soluble fiber, making it a wise choice for helping treat chronic constipation. One teaspoon of glucomannan powder contains 4 grams of fiber and is considered safe for short-term use even by children and those who are pregnant.

Constipation is a common pregnancy complaint. Research indicates that glucomannan is a more effective treatment option for relieving constipation than magnesium hydroxide (used in Mylanta and Milk of Magnesia) during the third trimester of pregnancy.

Another way that glucomannan can help relieve constipation is through its prebiotic properties. Glucomannan has been shown to stimulate the growth of Bifidobacteria and Lactobacilli in constipated adults. Bifidobacteria and Lactobacilli growth due to glucomannan intake has been demonstrated to improve bowel movements.

Possible Side Effects

Glucomannan supplements are generally considered safe when taken short-term as directed. However, there is not much known about the safety of using glucomannan as a health supplement long-term. Common side effects mostly include gastrointestinal issues such as increased gas, diarrhea, bloating, and stomach pain.

Glucomannan is highly absorbent, soaking up 50 times its weight in water. This can lead to blockages in the esophagus or intestines if you do not consume it with enough liquid. Be sure to drink at least 8 ounces of water when taking glucomannan.

If you are on medications such as those for treating cholesterol or diabetes, it is vital that you speak to your doctor about taking glucomannan.

Dosage and Preparation

There are no official guidelines or requirements for taking glucomannan supplements. Consuming up to 9 grams (9,000 milligrams) per day, split across three to four doses is considered safe. Consume glucomannan with water or another liquid and aim to drink more overall when taking it as a supplement.

Research on glucomannan supplementation for digestion has shown adding 4.5 grams per day to low-fiber diets increased the frequency of bowel movements in slightly constipated adults by 30% and improved their gut microbiome balance. 

For type 2 diabetic patients with hyperlipidemia, research findings suggest 3.6 grams per day for therapeutic effects. However, it is imperative that you speak to a healthcare provider before using glucomannan if you have diabetes or any other medical condition. Glucomannan powders, capsules, and tablets are commonly available in doses that range from 500 to 2,000 milligrams.

What to Look For

Dietary supplements are not typically regulated or evaluated for efficacy in the United States. For this reason, look for brands that carry a certification from an independent certifying body like the U.S. Pharmacopeia (USP), ConsumerLab, or NSF International. These organizations perform independent testing and can help ensure quality.

You should also speak to a healthcare provider about how this supplement might interact with existing medications. They also can advise you about dosing given you individual medical history.

Frequently Asked Questions

  • What are the best food sources of glucomannan?

    Glucomannan is found in shirataki noodles, which are made from konjac root. Shirataki noodles are a good stand-in for regular noodles or pasta in reduced calorie or low-carb diets.

  • When should I take glucomannan?

    There is no set time when you should take glucomannan. But if you plan to use it for increasing feelings of fullness, it may be best to take it prior to meals. Be sure to consume at least 8 ounces of water when you take glucomannan.

  • How much fiber is in glucomannan?

    One teaspoon of glucomannan powder from konjac root contains 4 grams of fiber.

8 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Rachel MacPherson, BA, CPT
Rachel MacPherson is a health writer, certified personal trainer, and exercise nutrition coach based in Montreal.