Glucomannan, or glucomannan konjac, is a supplement that’s used for maintaining a healthy weight, controlling blood sugar, and relieving constipation, among other health issues. It’s only recently become popular in the United States and Europe, but Asian cultures have enjoyed its benefits for thousands of years. The positive effects of glucomannan, including its impact on cholesterol and the immune system, have become the focus of extensive research.
Glucomannan: A Brief History
For the past two decades, the use of glucomannan as a dietary supplement and food additive has been on the rise in Europe and the United States. Japan, China, and Southeast Asia, however, have enjoyed konjac glucomannan as both a healthy food and traditional medicine for more than 2,000 years. The use of glucomannan can be traced back to an old Chinese poem from the third century. It is thought that Korean Buddhists brought it to Japan in the sixth century. In traditional Chinese medicine, glucomannan is believed to help with asthma, hernia, cough, burns, skin conditions, and other ailments.
What Are the Health Benefits of Glucomannan?
Several clinical trials have evaluated the impact of glucomannan, and the results confirmed many beneficial effects. It's shown to:
- Encourage normal body weight
- Reduce food cravings
- Support normal blood sugar
- Promote healthy, balanced cholesterol
Additionally, glucomannan has the potential to act as a therapy for insulin resistance syndrome. It enhances the immune system in the gut. Glucomannan also has a positive effect on triglycerides, total cholesterol, LDL cholesterol, and fasting blood glucose.[4, 5]
Glucomannan & Weight Loss
Glucomannan’s claim to weight loss is owed to its ability to absorb water quickly and form a gel which fills the stomach, giving you a feeling of being full. Food calories that get caught up in this gel are more likely to be excreted out of the body rather than be absorbed. It also reduces the appetite-inducing hormone ghrelin.
A 2015 study suggested that glucomannan supplementation reduced both body fat and weight without the loss of lean mass or bone density sometimes associated with weight loss. In further studies, when compared to ineffective supplements, the use of a glucomannan supplement by overweight individuals prompted significant weight loss.
Glucomannan & Cholesterol
In most Western countries, more than 50 percent of the population have high cholesterol levels. A dietary fiber with significant cholesterol-lowering effects, either as a dietary supplement or as a natural component of the diet, glucomannan has the potential to promote normal cholesterol. A double-blind, placebo-controlled study found that daily ingestion of the herb resulted in the reduction of total cholesterol levels by 10 percent.
Glucomannan & Fasting Blood Glucose
Your pancreas releases insulin to lower blood sugar, breaking it down so that the body can store it for later or use it right away for energy. High fasting blood sugar means that your body is unable to complete this process effectively. Over the long term, this can lead to diabetes.
Several studies have evaluated the natural benefits of glucomannan for patients with diabetes. A 2006 study examined the effects of plant sterols and glucomannan on diabetic subjects. The results suggest that glucomannan combined with plant sterols substantially improves plasma LDL cholesterol concentrations.
In another study, fasting blood glucose levels were significantly reduced after konjac food was ingested for one to two months, suggesting that konjac food may help promote normal blood sugar.
Can Glucomannan Help With Constipation?
When it comes to relieving occasional constipation, glucomannan has much of the same potential as psyllium, a commonly used laxative. Constipation is a common condition in western countries, but dietary fiber, such as that found in glucomannan, can often help promote normal bowel movement frequency and consistency.
Constipation in Adults
Occasional constipation affects us all at one time or another, but natural remedies can help get things moving again. In one study, adult patients with constipation took a glucomannan supplement. Due to glucomannan’s natural fiber, the patients reported a significant improvement after taking the supplement for only a month. The results were long-lasting and had no major side-effects. Researchers concluded that glucomannan could be an effective therapeutic aid in the management of constipation.
Constipation in Children
Constipation is common in children and typically results from an unhealthy diet, a change in environment or schedule, or simply avoiding going to the bathroom. A 2004 study was done to evaluate whether a fiber supplement was beneficial for children who are constipated. It found that using a glucomannan supplement had a positive effect. Children who were already on laxatives still benefited from this fiber supplement.
Constipation During Pregnancy
Whether it’s due to stress, lack of exercise, a low fiber diet, or the uterus pressing up against the intestines, constipation happens frequently to women who are pregnant. Some remedies normally used to control constipation, like laxatives, can cause uterine contractions and dehydration.
In one study, pregnant females affected by constipation took a mixture containing glucomannan twice a day for one to three months. This therapy resulted in normal bowel movements. As a bonus, because of glucomannan’s hunger control properties, some women who experienced disproportionate weight gain were better able to curb food cravings.
Glucomannan & Exercise
Exercise is a good way to encourage a healthy body weight and overall wellness, but studies have shown that the benefits of exercise are multiplied when combined with a glucomannan supplement. In a study of people who were sedentary and overweight, a glucomannan supplement was added to a regular exercise regime. The results showed that proper exercise and a diet containing glucomannan encouraged weight loss more effectively than exercise alone.
A separate study confirmed these results. Daily glucomannan supplementation paired with regular exercise helped to reduce overall caloric intake. Fat mass in both males and females was significantly reduced.
Glucomannan & Your Gut
Over the last 25 years, much attention has been given to the role dietary fiber plays in the microbiota, particularly concerning prebiotics. Observational evidence shows that a diet high in fiber is linked to a reduced risk of heart disease, diabetes, and obesity. These results may be related to the effect of dietary fiber on the gut microbiota and its ability to promote healthy gut bacteria. Most research has shown that dietary fiber, like glucomannan, positively affects the gut.
Ways to Consume Glucomannan
Glucomannan is commonly available as a tablet, capsule, flour, or powder. Many people will simply take a capsule or tablet with water before meals or sprinkle a powder over their food.
Glucomannan is also a component of konjac flour, a popular ingredient in Asian cuisine. This flour is used to make a variety of noodles, most notably the shirataki noodle. Glucomannan as an ingredient is enjoyed for its texture, which tends to assume the taste of whatever foods with which it is cooked.
What’s the Best Serving Size?
Glucomannan is a powerful, bulk-forming supplement, so it’s best taken in small servings with plenty of water at first. You can gradually increase your serving size as your body acclimates. The recommended daily servings of glucomannan are:
- Relieving occasional constipation: 3 to 4 grams
- Promoting normal cholesterol: 4 to 13 grams
- Encouraging normal blood sugar: 500 to 700 mg of glucomannan per every 100 calories of food
- Supporting a healthy body weight: 2 to 4 grams before each meal[1, 17,18]
This table is only a guideline, consult a healthcare provider before use to find a serving size that works best for you.
What Are the Side Effects?
Side effects of glucomannan are rare, but some people may experience an allergic reaction including rash, itching, difficulty breathing, and swelling of the throat and mouth. Other potential side effects include:
One thing to consider is that capsules may be safer than tablets. Tablets can stick to the back of the throat, causing difficulty swallowing. This issue worsens when water is taken to wash the tablet down, causing the fiber to expand further.
Who Should Try Glucomannan?
Based on varying research and studies, glucomannan has been used by people who have constipation, high cholesterol, insulin resistance syndrome, type 2 diabetes, and people who want to lose weight and body fat. Although the benefits of glucomannan are many, consult your healthcare practitioner before beginning supplementation for advice and instructions.
What's Your Story?
- Keithley J, et al. "Glucomannan and obesity: a critical review." Altern Ther Health Med. 2005;11(6), 30-4. Accessed 6 Dec. 2017.
- Chua M, et al. "Traditional uses and potential health benefits of Amorphophallus konjac K. Koch ex N.E.Br." J Ethnopharmacol. 2010;128(2), 268-78. Accessed 6 Dec. 2017.
- Sood N, et al. "Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis." Am J Clin Nutr. 2008;88(4), 1167-75. Accessed 6 Dec. 2017.
- Vuksan V, et al. "Beneficial effects of viscous dietary fiber from Konjac-mannan in subjects with the insulin resistance syndrome: results of a controlled metabolic trial." Diabetes Care. 2000;23(1), 9-14. Accessed 6 Dec. 2017.
- Tester R, et al. "Beneficial health characteristics of native and hydrolysed konjac (Amorphophallus konjac) glucomannan." J Sci Food Agric. 2016;96(10), 283-91. Accessed 6 Dec. 2017.
- Bruno G. "Konjac: Root/glucomannan for weight control, blood lipids, and constipation." Supplement Science. Huntington College. hchs.edu. Nov. 2014.
- Kaats G, et al. "Konjac glucomannan dietary supplementation causes Significant fat loss in compliant overweight adults."J Am Coll Nutr. 2015 22:1-7.
- Birketvedt G, et al. "Experiences with three different fiber supplements in weight reduction." Med Sci Monit. 2005;11(1), PI5-8.
- Arvill A, et al. "Effect of short-term ingestion of konjac glucomannan on serum cholesterol in healthy men." Am J Clin Nutr.1995;61(3), 585-9.
- Yoshida M, et al. "Effect of plant sterols and glucomannan on lipids in individuals with and without type II diabetes." Eur J Clin Nutr. 2006;60(4), 529-37. Accessed 6 De 2017.
- Huang CY, et al. "Effect of Konjac food on blood glucose level in patients with diabetes." Biomed Environ Sci.1990;3(2), 123-31. Accessed 6 Dec. 2017.
- Passaretti S, et al. "Action of glucomannans on complaints in patients affected with chronic constipation: a multicentric clinical evaluation." Ital J Gastroenterol.1991;23(7), 421-5. Accessed 6 Dec, 2017.
- Loening-Baucke V, et al. "Fiber (glucomannan) is beneficial in the treatment of childhood constipation." Pediatrics. 2004;113(3 p1), e259-64.Accessed 6 Dec. 2017.
- Signorelli P , et al. "A clinical study of the use of a combination of glucomannan with lactulose in the constipation of pregnancy." Minerva Ginecologica.1996;48(12), 577-582. Accessed 6 Dec. 2017.
- Kraemer W, et al. "Effect of adding exercise to a diet containing glucomannan." Metabolism. 2007;56(8), 1149-58.
- Sawicki C, et al. "Dietary fiber and the human gut microbiota: application of evidence mapping methodology." Nutrients. 2017; 9(2), 125.
- "Glucomannan: how it works." Michigan Medicine. University of Michigan. uofmhealth.org. 2015.
- "Monograph - glucomannan capsule." Health Canada. Hc-sc.gc.ca. 2010.
- "Glucomannan: uses." Michigan Medicine. University of Michigan. uofmhealth.org. 2015.
- Henry D, et al. "Glucomannan and risk of esophageal obstruction." Br Med J (Clin Res Ed). 1986;292(6520), 591–592.
†Results may vary. Information and statements made are for education purposes and are not intended to replace the advice of your doctor. If you have a severe medical condition or health concern, see your physician.