Glucomannan vs Psyllium
Fibre is an integral component of a properly balanced diet, and its health benefits are well documented. Higher intakes of fibre are associated with lower body weight, improved digestive health and a reduced risk of cardiovascular disease and certain types of cancer.
According to the NHS, many members of the UK population do not have enough fibre in their diets, and the average intake of fibre in the UK is only around 18g per day. Adults should aim for a fibre intake of 30g per day.
Dietary fibre is provided exclusively by plant foods, and foods such as meat, fish and dairy products do not make any contribution to fibre intake.
There are two main types of fibre:
- Insoluble fibre
- Soluble fibre
Insoluble fibre cannot be digested by the body and passes through the digestive tract without being broken down. It adds bulk to stools, and some people find that it can help to reduce the transit time of food through the stomach and intestines. Sources of insoluble fibre in the diet include:
- Potatoes with skins
- High fibre breakfast cereals
Soluble fibre can be digested by the body, and during digestion, it attracts water to form a gel. Soluble fibre can have a role in reducing cholesterol, and people who suffer from constipation may benefit from increasing the amount of soluble in their diet. Sources of soluble fibre in the diet include:
- Oats, barley and rye
- Golden linseeds
The British Nutrition Foundation recommends the following methods of increasing fibre intake:
- Eat a high fibre cereal for breakfast
- Replace white bread with granary or wholemeal versions
- Choose wholegrain version of pasta and rice
- Eat potatoes with their skins
- Snack on fruit, vegetable sticks, nuts and seeds
- Increase your intake of vegetables
- Use more pulses and beans in cooking
- Have fresh, dried or canned fruit for dessert
Dietary fibre can confer a range of health benefits, and supplements can provide a convenient way of boosting the amount of fibre you consume each day. Supplements also make it easy to monitor and regulate your fibre intake, which is a factor since current advice is to increase the amount of fibre in diet gradually, in order to give your digestive system time to adjust. Two of the most popular types of fibre that people choose as supplements are:
How Do Glucomannan and Psyllium Work?
Both glucomannan and psyllium fall into the category of fibre known as soluble fibre.
Once inside the digestive system, both glucomannan and psyllium husks absorb water. This creates a bulky mass that softens stools and aids the transit of waste through the digestive tract, helping to improve the symptoms of constipation.
Although, they are both types of soluble fibre and therefore have similar properties generally, research on glucomannan and psyllium points to specific benefits for supplementing with each one individually.
Supports Weight Loss
In a randomised, double-blind placebo-controlled trial, that was published in 2015 in the Journal of the American College of Nutrition, 83 participants were assigned to take either 3g of a glucomannan supplement or placebo for a period of 60 days. The results of the study showed that the participants who regularly took glucomannan lost significantly more weight than those who took the placebo. The author also reported that the observed reduction in body weight was achieved without the loss of lean muscle mass and bone density that typically accompanies weight loss.
Maintains Healthy Cholesterol Levels
A number of trials have investigated the effects of glucomannan on cholesterol levels. In order to better understand the impact that glucomannan has on various characteristics of metabolic syndrome such as cholesterol, Sood et al pooled existing evidence in a meta-analysis and reviewed the results of 14 individual randomised control trials.
The results of the meta-analysis, which was the first of its kind, were published in the American Journal of Clinical Nutrition in 2008. In their conclusion, the authors wrote that glucomannan appears to beneficially affect levels of total cholesterol and low-density cholesterol and that future research is warranted.
Helps to Balance Blood Sugar Levels
The benefits of supplementing with glucomannan to patients with type 2 diabetes were evaluated in a single-blind, placebo-controlled trial conducted by Chearskul et al. The trial consisted of two separate experiments, in which the effects of glucomannan on blood glucose control and cholesterol were examined in 10 men and 10 women with type 2 diabetes mellitus. In the first experiment, either placebo or 1g of glucomannan was administered 30 minutes before a 75g load of glucose, to measure the effect of glucomannan on glucose absorption and insulin secretion.
In the second experiment, the effects of supplementing with either placebo or 3g of glucomannan per day for a period of 4 weeks were assessed in terms of blood sugar and lipid levels. The result of the study showed that glucommanan attenuated the rise in blood sugar following the glucose load and that long-term supplementation with glucomannan reduced the increase in blood sugar level following a glucose tolerance test. The authors suggested that glucomannan may be useful to patients with type 2 diabetes mellitus in controlling their blood sugar levels.
Constipation can affect anyone of any age, and chronic constipation is particularly common in adults over the age of 60. One of the main factors contributing to constipation is inadequate fibre in the diet, and diet and lifestyle recommendations are usually the first steps in the treatment of constipation. The American College of Gastroenterology Constipation Task Force assessed treatment options in the management of chronic constipation in a systematic review. The research team made the evidence-based recommendation that psyllium can help increase stool frequency in patients with chronic constipation.
Irritable Bowel Syndrome
Irritable bowel (IBS) is a relatively common condition and it is thought that up to one in five people will be affected by the condition at some point during their life. The symptoms and severity of IBS vary from person to person, and it is a complex syndrome that is often difficult to manage effectively. In the August 2014 edition of Digestion, Trinkley and Nahata presented the evidence supporting the various treatments of specific symptoms associated with IBS. After critically evaluating a wide range of studies on the management of IBS, the authors concluded that psyllium has found to be effective in improving the symptoms of IBS, and that efficacious dosages started from 3g twice a day.
Choosing the Right Fibre Supplement
The main difference between glucomannan and psyllium is their source. Glucomannan is derived from the root of the konjac plant, whereas psyllium husks are taken from the Plantago ovate shrub.
As they are both sources of soluble fibre, glucomannan and psyllium husks have a range of common characteristics. They share similar properties and determining which one is right for you will depend on your individual set of circumstances.
A trial period with each supplement might be useful in helping you discover which one you find more effective. Regardless of which you choose, it is important to drink enough water while taking either glucomannan or psyllium husks. You should also consult your general practitioner before taking fibre supplements if you are using medication or have an existing health condition.
1. British Nutrition Foundation, 2016. “Dietary fibre”. URL: . [Accessed 15th mar 2016]
2. Heart UK, “Oats, barley and other soluble fibre rich foods”. URL: . [Accessed 15th Mar 2016]
3. NHS Choices, 2015. “How to get more fibre into your diet”. URL: . [Accessed 15th mar 2016]
4. Hartley L et al. Dietary fibre for the primary prevention of cardiovascular disease. The Cochrane Database of Systematic Reviews. 2016 Jan.
5. Katts GR, Bagchi D, Preuss HG. Konjac Glucomannan Dietary Supplementation Causes Significant Fat Loss in Compliant Overweight Adults. Journal of the American College of Nutrition. 2015 Oct
6. Sood N, Baker WL, Coleman CI. Effect of Glucomannan on Plasma Lipid Concentrations, Body Weight, and Blood Pressure: Systematic Review and Meta-Analysis. American Journal of Clinical Nutrition. 2008 Oct.
7. Chearskul et al. Glycaemic and Lipid Response to Glucomannan in Thais with Type 2 Diabetes Mellitus. Journal of the Medical Association of Thailand. 2007 Oct.
8. Trinkley KE, Nahata MC. Medication Management of Irritable Bowel Syndrome. Digestion. 2014 Jul.
9. Slavin J. Fibre and Prebiotics: Mechanisms and Health Benefits. Nutrients. 2013 Apr.
10. Mounsey A, Raleigh M, Wilson A. Management of Constipation in Older Adults. American Family Physician. 2015 Sep.
11. Brandt LJ et al. Systematic review on the Management of Chronic Constipation in North America. The American Journal of Gastroenterology. 2005.