21% off £35
Code:BAG21
Curious about glucomannan and why it's popping up in so many supplements? Here’s what you need to know about this natural fibre, how it works and what to consider before trying it
Our top picks
Just 114 calorie
SlimExpert
Holland & Barrett SlimExpert Apple Cinnamon Flavour Porridge 10 Sachets
Buy 1 Get 1 Free
18+
£5.00
£9.99
Looking to support your digestion and help with fullness? Glucomannan, a plant-based fibre, has been gaining attention for its wellness benefits – particularly as research indicates its ability to help you feel fuller for longer and support healthy digestion. Its standout feature is its ability to absorb water – expanding in your stomach, helping to create a lasting sense of fullness and keep things moving smoothly.
We’ve broken down what glucomannan is, how it works in the body and the different ways people are incorporating it into their routines. So whether you're curious about glucomannan or just exploring fibre supplements, we’ve got you covered.
What’s glucomannan?
Glucomannan is a natural, water-soluble fibre that comes from the root of the konjac plant (also known as the elephant yam) which has been grown and used in Southeast Asia for centuries. Traditionally, konjac root has been used in Japanese and Chinese cooking, often found in foods like konjac jelly, noodles, rice and other low-calorie dishes.
But what makes glucomannan stand out is its incredible ability to absorb water. In fact, it can soak up more than 50 times its own weight in liquid.1,2 This unique property helps it expand in your stomach, which can make you feel fuller after eating – just like other types of fibre (but even more so).3 That’s one of the main reasons it’s become popular as a supplement.
You'll also see glucomannan listed as a food additive under the name E425, where it’s used as a thickener or bulking agent in products like noodles and pasta.4 But it can also be taken as a supplement, either in tablet form or as a powder you mix with water.
It’s simple to take and easy to include in your daily routine, especially if you're looking for ways to support your fibre intake.
What does glucomannan do in the body?
Glucomannan works by absorbing water in the stomach and intestines, forming a soft, bulky gel.5
Like other soluble fibres, glucomannan may also help with satiety. Because it swells in the stomach, it can create a sensation of fullness, which might help reduce appetite and delay the emptying of the stomach – helping you feel satisfied for longer after eating.3
Research also suggests that glucomannan supports healthy cholesterol.6
How does glucomannan work?
Glucomannan has been studied for its potential role in supporting weight loss. While the evidence is interesting, it’s important to remember that individual results can vary and no supplement is a magic fix.
One study found that glucomannan can help with modest weight loss – people taking it lost just under 1 kg more than those on a placebo. The effect was a bit stronger in women, smaller groups and shorter trials. But the results varied quite a bit between studies, so while glucomannan shows promise, it’s not a guaranteed fix. It may offer small support, especially when combined with healthy habits, but more research is needed to know for sure who benefits most.7
If you’re considering trying glucomannan, it’s best used alongside – not instead of – a balanced, nutritious diet and a healthy lifestyle. Supplements can play a supporting role, but they’re not a replacement for real food and good habits. It’s also important to check with a healthcare professional before adding any new supplements into your routine.
How much glucomannan should I take?
The European Food Safety Authority (EFSA) suggests the beneficial effect of glucomannan is obtained with a daily intake of 3g per day to support digestive health and weight management (in the context of an energy-restricted diet). This is typically split into three equal doses of 1g each throughout the day and taken with one to two glasses of water before meals – especially if you're following a calorie-controlled diet.8,9
At 4g per day, glucomannan may also help maintain healthy blood cholesterol levels.8,9
Just a heads-up – if you have trouble swallowing or aren't drinking enough fluid, there’s a risk of choking. It’s important to take glucomannan with plenty of water to help it go down smoothly and make sure it reaches the stomach safely.
What are the side effects of glucomannan?
For most adults, glucomannan is generally well tolerated and considered safe when taken as directed. However, as with any supplement, people can respond differently – and some may experience mild side effects, especially when first starting out.
Possible side effects may include:10
- bloating – a feeling of fullness or swelling in the stomach
- wind (flatulence) – increased gas
- softer stools – your bowel movements might be looser than usual
- diarrhoea – in some cases, it can speed things up a bit too much
These effects are usually mild and tend to settle as your body adjusts. They’re also considered quite uncommon in most people.
If you're new to glucomannan, it can help to start with a smaller amount and gradually increase, while drinking plenty of water. And, of course, if you have any concerns or existing health conditions, it’s always best to check with a healthcare professional before adding any new supplement to your routine.
Our favourite glucomannan supplements
If you're looking for a breakfast that’s both comforting and clever, SlimExpert Apple & Cinnamon Porridge might be just the thing. It offers all the goodness of traditional oats, but with a twist.
Each sachet contains just 114 calories, with plenty of fibre and protein to support your muscles. It’s naturally flavoured, vegetarian-friendly and has no added sugar – all while tasting like a cosy bowl of apple and cinnamon.
What makes it different from regular porridge is the added blend of glucomannan, chromium and inulin. Ideal as a light breakfast or satisfying snack, SlimExpert porridge is a simple but delicious way to support your fibre intake.
As always, weight loss results vary from person to person and are best achieved as part of a balanced diet and healthy lifestyle.
If you’re looking to support your wellness goals with a bit of extra help, H&B’s Glucomannan and Chromium Capsules could be worth considering. They’re packed with konjac fibre – a plant-based ingredient that’s naturally low in calories but high in soluble fibre.
It works by helping to promote a lasting sense of fullness, which may make it easier to manage your appetite.
The capsules also contain chromium, an essential mineral that plays a role in maintaining normal blood glucose levels and supporting the metabolism of fats, proteins and carbohydrates.
While these capsules may offer useful support, they’re intended for adults only and should always be taken as part of a healthy, varied diet and lifestyle.
In search of a natural way to support your weight management efforts? Holland & Barrett’s Glucomannan Capsules could be a helpful addition to your routine.
Glucomannan is a type of soluble fibre derived from the root of the konjac plant. It’s known for its impressive ability to absorb water and expand in the stomach.
When taken as part of an energy restricted diet, glucomannan has been shown in studies to contribute to weight loss. The beneficial effect is obtained with a daily intake of 3g a day, (divided into three doses of 1g servings each) and taken with one to two glasses of water before meals.
These capsules are designed for adults and aren’t suitable for anyone under 18. And as with any supplement, it should be used to complement a healthy lifestyle – not replace one.
The final say
So, that’s glucomannan in a nutshell – a natural fibre with some interesting properties and a growing presence in the world of supplements. Whether you’re simply curious about how it works, looking to better understand the science behind it or exploring the different products available, it’s always worth being well-informed.
Remember, while supplements like glucomannan can play a role in some people’s routines, they’re not a magic solution or a replacement for a balanced diet and healthy lifestyle. Everyone’s body is different, and what works for one person might not suit another.
If you’re thinking about trying something new, especially when it comes to your health, it’s a good idea to have a chat with a healthcare professional first.
This article provides informational advice and is not a substitute for medical care. Curated by experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.
1. Keithley JK, Swanson B, Mikolaitis SL, DeMeo M, Zeller JM, Fogg L, et al. Safety and Efficacy of Glucomannan for Weight Loss in Overweight and Moderately Obese Adults. Journal of Obesity [Internet]. 2013;2013:1–7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3892933/
2. Glucomannan - an overview | ScienceDirect Topics [Internet]. www.sciencedirect.com. Available from: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/glucomannan
3. Guo L, Yokoyama W, Chen M, Zhong F. Konjac glucomannan molecular and rheological properties that delay gastric emptying and improve the regulation of appetite. Food Hydrocolloids [Internet]. 2021 Nov 1;120:106894. Available from: https://www.sciencedirect.com/science/article/pii/S0268005X21003106?casa_token=3LTp1utLxkIAAAAA:dmwDRuLJD9Ju6tbI_B4wq4d0-4_7OstbqK5o15GGDwgNRDyOEvfiF_vCJ4M41pZ7KhFh4O4pyw
4. Mortensen A, Aguilar F, Crebelli R, Di Domenico A, Frutos MJ, Galtier P, et al. Re‐evaluation of konjac gum (E 425 i) and konjac glucomannan (E 425 ii) as food additives. EFSA Journal. 2017 Jun;15(6).
5. Chen HL, Cheng HC, Liu YJ, Liu SY, Wu WT. Konjac acts as a natural laxative by increasing stool bulk and improving colonic ecology in healthy adults. Nutrition. 2006 Nov;22(11-12):1112–9.
6. Shah BR, Li B, Wang L, Liu S, Li Y, Wei X, et al. Health benefits of konjac glucomannan with special focus on diabetes. Bioactive Carbohydrates and Dietary Fibre. 2015 Apr;5(2):179–87.
7. Mohammadpour S, Amini MR, Shahinfar H, Tijani AJ, Shahavandi M, Ghorbaninejad P, et al. Effects of glucomannan supplementation on weight loss in overweight and obese adults: A systematic review and meta-analysis of randomized controlled trials. Obesity Medicine. 2020 Sep;19:100276.
8. Re-evaluation of konjac gum (E 425 i) and konjac glucomannan (E 425 ii) as food additives | EFSA [Internet]. www.efsa.europa.eu. 2017. Available from: https://www.efsa.europa.eu/en/efsajournal/pub/4864
9. Regulation - 432/2012 - EN - EUR-Lex [Internet]. Europa.eu. 2024 [cited 2025 Jul 16]. Available from: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32012R0432&qid=1751638610124
10. National Institutes of Health. Dietary Supplements for Weight Loss [Internet]. Nih.gov. 2017. Available from: https://ods.od.nih.gov/factsheets/WeightLoss-HealthProfessional/
Related Articles
Shop by wellness goal
