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Glucomannan is a type of dietary fibre made from elephant yam, the root of the konjac plant. It’s a common dietary supplement that’s gaining a lot of attention for its possible health benefits. Glucomannan benefits could include reducing body weight, easing constipation, lowering high cholesterol, and helping to regulate blood sugar levels. However, with only limited scientific support, you should still take glucomannan with caution for now.
Glucomannan: A New Superfood?
These days, there are so many foods and supplements out there that claim to change your life. And we know it can be difficult to tell the superfoods from the scams.
That’s why we’re here to help you navigate the science.
In this article, we’re talking you through glucomannan, the dietary fibre made from the root of the konjac plant. Its supporters claim that it can do wonders for obesity, diabetes treatment, and constipation relief.
But is this true? Let’s take a look. Here’s the truth behind glucomannan benefits.
What is Glucomannan?
Glucomannan is a type of dietary fibre made from elephant yam, the root of the South Asian konjac plant.
It’s available as a food supplement, but it is also added to drink mixes as a thickener and to foods like pasta, flour, and other carbohydrates as an emulsifier. Konjac flour is a regulated food additive used as a gelling agent or stabiliser in many food products (that’s why you might come across konjac glucomannan referred to with the E-number E425-ii).
So, why is it thought to bring health benefits?
Primarily, because of its incredible power to absorb water. According to clinical trials, glucomannan can absorb up to 50 times its weight in water – making it one of the most viscous dietary fibres around. It’s this fact that’s behind glucomannan’s possible health benefits.
Glucomannan Benefits, According to Science
So, what are glucomannan’s benefits? Here’s what the science says:
1. Glucomannan may help weight loss
Fibre can help weight loss for several well-established reasons:
- Fibre can help to make you feel full
- It can slow down the process in which your stomach is emptied
- It reduces the proteins and fats that are absorbed from your food
- It’s a prebiotic that feeds the friendly bacteria in your gut. Find out more: Prebiotic vs Probiotic: What’s the Difference?
As glucomannan is a particularly dense fibre, it’s marketed as having a more radical effect than other fibres as a weight loss supplement. But that evidence is not always so clear:
- One clinical study into 176 overweight adults found that supplementing a reduced-calorie diet with glucomannan significantly increased the amount of weight lost compared to a placebo. However, the study compared different fibres, and there was not much difference between their effects and those of glucomannan.
- Another study gave obese adults a glucomannan supplement before breakfast, lunch, and dinner for eight weeks. The study found no benefit for weight loss compared to a group who took a placebo.
- However, two other studies (this one and this one) have found that glucomannan supplementation can improve weight loss.
While the results are not conclusive, there are promising signs to support the use of glucomannan for weight loss.
2. Glucomannan may reduce cholesterol
Glucomannan is thought to reduce cholesterol levels by preventing the absorption of dietary cholesterol in your blood.
- According to a large meta-analysis of 14 studies, glucomannan was found to cause a significant reduction of low-density lipoprotein, or LDL cholesterol (also known as bad cholesterol). The same review found that glucomannan can also reduce total cholesterol levels and triglycerides.
- Other studies – including this one from 1995 and, more recently, this systematic review from 2017 – have confirmed these findings.
This means when consumed as part of a healthy, active lifestyle, glucomannan can be hugely helpful in reducing the risk of heart disease and cardiovascular disease.
3. Glucomannan appears to ease constipation
There is good evidence to suggest that glucomannan can help treat constipation. It’s a so-called ‘bulk-forming laxative’, which can help to ensure that everything in your gut moves as it should.
4. Glucomannan can help regulate blood glucose
There are also claims that glucomannan can help lower blood sugar levels in people with type 2 diabetes. Scientific studies into blood sugar levels seem to suggest this is true.
There is further good news for people with diabetes mellitus. Glucomannan seems to reduce cholesterol and the risk of coronary heart disease in diabetes patients, too.
Other Benefits of Glucomannan
Alongside those covered above, there are further benefits that have been suggested:
- Glucomannan could reduce blood pressure: There is some limited evidence to suggest that this could work. However, the jury is still out.
- Clinical trials suggest it could help an overactive thyroid when used alongside methimazole and propranolol.
- The fibre could ease dumping syndrome, which is sometimes experienced after stomach surgery.
How to Take Glucomannan?
Like every supplement and medicine, glucomannan needs to be taken in the optimal way to have an effect.
Usually, a gram of glucomannan powder is enough to have an impact. But studies have found that 2 to 4 grams of the fibre are well-tolerated. If you’re taking glucomannan for weight loss, you should take it before a meal.
Important: Take glucomannan with a glass of water. The fibre is banned in Australia as it’s considered a choking hazard. In some circumstances, the powder has expanded in people’s throats, impeding their breathing.
Possible glucomannan benefits include helping weight loss, reducing blood sugar, and reducing cholesterol. While the evidence suggests it works, the dietary fibre has not yet received full medical approval. More research is needed.
Why is Glucomannan banned in Australia?
Glucomannan is banned in Australia because it may be a possible choking hazard.
Side effects of glucomannan include a swollen stomach and frequent bowel movements. But it is the risk of the powder swelling in your throat that has been most concerning. This can happen if you do not take the tablet with enough water, as Product Safety Australia makes clear.
In the EU, some konjac products are banned for the same reason.
Is Glucomannan Good for Gut Health?
As a prebiotic fibre, glucomannan may offer benefits for gut health – including promoting good gut bacteria. But there is not yet enough evidence to say for sure.
Does Glucomannan Cause Constipation?
No, there is no evidence that glucomannan causes constipation. Instead, it’s believed to help your bowel movements, as it works as a form of laxative.