How to choose a fibre supplement: a practical guide

How to choose a fibre supplement and find the best fibre for you: 8 clear criteria, a table of what to check on the label and a simple way to compare the price per serving.

The best fibre is not the one with the loudest claims, but the one with a clear composition that suits you. Drinkable fibre usually comes as a powder that you stir into water and drink, and fibre supplements are worth comparing using the same set of criteria. They differ not only in the amount of fibre, but also in its sources, serving size, other ingredients and how they are taken. So when you choose a fibre supplement, look beyond the front of the pack to the nutrition declaration and the list of ingredients.

This guide draws on recommendations from the European Food Safety Authority (EFSA), EU food labelling and food supplement law, information from the Harvard T.H. Chan School of Public Health, Mayo Clinic and the UK National Health Service (NHS), and peer-reviewed research. You will find the sources at the end of the guide, and they are marked with numbers in the text, for example [1].

If you are not yet sure how much fibre you need, start with our article “How much fibre do you need per day?”. We write more about the most common ingredient in fibre supplements in “Psyllium: what it is and how to take it”.

What are fibre supplements and when might you need one?

Fibre supplements are food supplements that contain concentrated plant fibre, most often psyllium husk, inulin, glucomannan, oat or other cereal bran, and sometimes fruit and berry powders. EFSA considers 25 g of fibre a day to be adequate for normal laxation in adults [1], yet many people get much less than that from food [2].

It also helps to know what a supplement cannot replace. Mayo Clinic and Harvard researchers stress that fibre-rich foods should come first: vegetables, fruit, wholegrains, pulses, nuts and seeds, because they also provide vitamins, minerals and other useful nutrients [2, 3]. A fibre supplement can help top up your diet when you get too little fibre from food. EU law says the same thing: every food supplement label must state that it should not replace a varied diet [4].

The best fibre: 8 criteria for choosing a fibre supplement

When you see several fibre supplements on a shelf or online, compare them in this order:

1. Fibre per 100 g and per serving. This is the first and most objective number.
2. A mix of soluble and insoluble fibre. Different fibres behave differently.
3. Ingredients and additives. What else is in the powder besides fibre.
4. Added sugar. Whether the sweetness comes from fruit or from added sugar and syrups.
5. Serving size. How much you need to take to get the stated amount of fibre.
6. Lab testing and transparency. What the maker tested and whether they explain it openly.
7. Taste and how it mixes. Whether you will enjoy drinking it every day.
8. Price per serving. Not the price of the pack, but the cost of one serving and of one gram of fibre.

1. Fibre per 100 g and per serving

In the nutrition declaration, look for the line “fibre”. It may be shown per 100 g of product and per serving. EU law sets clear thresholds: a product may be called a source of fibre if it contains at least 3 g of fibre per 100 g, and high in fibre if it contains at least 6 g per 100 g [5]. Fibre supplements usually contain far more than this, so it is worth comparing the exact grams.

The amount per 100 g shows how concentrated a product is, while the amount per serving shows how much fibre you actually get. A product can be very concentrated, but if the recommended serving is small, one serving will still give you little fibre.

2. A mix of soluble and insoluble fibre

Soluble fibre forms a gel or a thick mass in water, while insoluble fibre adds bulk to stool [3, 6]. Most plant foods contain both types. Still, the word “soluble” alone does not tell you how a fibre will behave. Researchers also look at whether a fibre forms a viscous gel, how much water it holds and how much of it gut bacteria ferment [7]. Psyllium, for example, forms a gel, whereas inulin is a soluble fibre that does not gel and is readily fermented [7].

So it is more useful to look not at percentages on the pack, but at whether the product contains several types of fibre and whether it is clear which plants they come from. We explain the differences in more detail in “Soluble and insoluble fibre”.

3. Ingredients and additives

EU law requires the list of ingredients to include all ingredients in descending order of weight [8]. This means the first ingredient on the list is the one the product contains most of. If the fibre source is only third or fourth on the list, it is worth finding out what makes up the rest.

• Fibre sources. Are the plants clearly named, for example “psyllium (Plantago ovata) husk”, or is there just the general word “fibre”?
• Fillers. Some powders contain a lot of ingredients that add volume but not fibre.
• Sweeteners, flavourings and colourings. They are not banned, but it is worth knowing whether the taste comes from real fruit or from a flavouring.
• Allergens and dietary needs. Check whether the product is free from gluten and lactose and whether it is suitable for vegans, if that matters to you.

4. Added sugar

The line “of which sugars” in the nutrition declaration shows the total sugar content: both the sugar naturally present in fruit or berries and any added sugar. To find out whether sugar has been added, look at the ingredients: sugar, glucose or fructose syrup, dextrose, honey, syrups. A small amount of natural sugar from freeze-dried fruit is not the same as sugar added for taste.

5. Serving size

A food supplement label must state the recommended daily portion and a warning not to exceed it [4]. Compare how many grams of powder make up one serving and how much fibre that serving provides. The smaller the serving for the same amount of fibre, the more concentrated the product.

Serving size also matters for how you feel. Increasing fibre suddenly can cause bloating, wind or cramps, so it is best to increase it gradually and drink more fluids [2, 3, 9].

6. Lab testing and transparency

The phrase “lab tested” does not say much on its own. It is worth knowing what exactly was tested (fibre content, microbiological parameters), where the test was done and whether the result matches the label. Remember that a composition test confirms how much fibre is in a sample, but it does not prove any health effect.

Transparency also means careful wording. In the EU, foods may only carry health claims that EFSA has assessed and the European Commission has authorised, and only under set conditions [10]. Absolute promises, for example that a product “cleanses the body”, should raise questions.

7. Taste and how it mixes

The best fibre supplement is the one you will actually take every day. Gel-forming fibres such as psyllium and glucomannan thicken quickly in water [7, 11], so stir and drink straight away. This is normal and not a flaw in the product. Unflavoured powders are good for stirring into porridge or yoghurt, while flavoured ones are easier to drink with water.

8. Price per serving

The price of the pack is misleading, because packs differ in size and number of servings. The simplest way to compare:

1. Price per serving = price of the pack ÷ number of servings.
2. Price per gram of fibre = price per serving ÷ grams of fibre per serving.

For example, if a pack costing €20 contains 40 servings of 3 g of fibre each, one serving costs €0.50 and one gram of fibre about €0.17. This lets you compare packs of different sizes.

What to check on a fibre supplement label

All the criteria above fit on a single label. Here is where to look:

How to start taking drinkable fibre safely

Even the best fibre only works for you if you take it the right way. A few simple principles:

• Start with a small serving. Increase your fibre gradually over a few weeks so your gut has time to adjust [3, 9].
• Drink enough water. Fibre draws water into the bowel, so more fibre means you need more fluids [9]. Always take swelling fibres such as psyllium with plenty of water, because taking them with too little fluid carries a risk of choking [11].
• Avoid them if you have trouble swallowing. Swelling fibres are not recommended if you have difficulty swallowing [11].
• Keep them apart from medicines. Swelling fibres can delay the absorption of some medicines. EMA advises taking psyllium at least half an hour to an hour before or after other medicines [11], and if you take several medicines, talk to your doctor or pharmacist.
• Follow the label. Do not exceed the recommended daily portion [4].

Important: this information is about fibre and nutrition in general. It does not describe the effect of any specific product and does not replace medical advice.

When should you talk to a doctor before taking a fibre supplement?

A fibre supplement is a food, not a medicine, so it cannot replace treatment. Talk to your doctor or pharmacist if you:

• take medicines, especially several different ones;
• have a long-term condition, such as diabetes or a digestive disease;
• are pregnant or breastfeeding;
• want a fibre supplement for a child: only do this after speaking to the child's doctor;
• have trouble swallowing or have had a narrowing of the oesophagus.

The NHS also advises seeing a doctor if you notice blood in your stool, unusual changes in bowel habits that continue, unexplained weight loss, persistent tummy pain or a lump in your tummy [12]. In these cases it is important to find the cause rather than try to mask it with supplements.

How does the fruttberry fibre blend measure up against these criteria?

We created fruttberry out of a personal need: we wanted a fibre blend that would be pleasant to drink every day. Here are its facts, set out by the same criteria, so you can compare for yourself.

Ingredients

• Psyllium husk is the base of the blend.
• Agave inulin is a soluble fibre that is fermented in the gut. We write more about it in “Inulin: what it is”.
• Freeze-dried strawberries (12%) and blackcurrants (8%) provide taste and colour from real berries, not from flavourings.
• Glucomannan from konjac tubers is another soluble fibre.

Fibre content and serving

Stir one teaspoon into 200–250 ml of water and drink it straight away, then increase the amount every 3–4 days. Psyllium and glucomannan swell, so always take the blend with enough water: taking it with too little fluid carries a risk of choking. If you have trouble swallowing, do not take this kind of fibre.

Which pack should you choose?

The blend is the same in both packs, only the format differs. For home, the 250 g jar (about 50 servings of 5 g) is the most practical, and for work and travel there are 30 single servings of 5 g. You can easily work out the price per serving with the formula above: the larger pack costs less per serving.

All fruttberry dietary fibre products in one place.

Frequently asked questions about the best fibre and fibre supplements

Which fibre is the best?

There is no single best fibre for everyone. The best fibre for you has a clear composition, provides enough fibre per serving, contains no unnecessary additives and is easy to take every day. Food should be your first source of fibre [2, 3].

Are all fibre supplements the same?

No. They differ in fibre sources, fibre per serving, other ingredients and serving size. Different fibres also behave differently: some form a gel, others are readily fermented by gut bacteria [7].

What should I compare: fibre per 100 g or per serving?

Both. The amount per 100 g shows how concentrated a product is, and the amount per serving shows how much fibre you actually get from one serving.

Does “lab tested” mean a product is effective?

No. A composition test confirms how much fibre is in the tested sample, but it does not prove a health effect. In the EU, health claims are only allowed if they are authorised and only under set conditions [10].

Do I have to take drinkable fibre with water?

Yes. Swelling fibres must be taken with enough fluid, as stated on the label, because too little water carries a risk of choking [11]. You also need more fluids when you increase the fibre in your diet [9].

Sources

1. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibre. EFSA Journal. 2010;8(3):1462.
2. Harvard T.H. Chan School of Public Health. Fiber. The Nutrition Source. Reviewed 2022.
3. Mayo Clinic. Dietary fiber: Essential for a healthy diet. Reviewed 2026.
4. European Parliament and Council. Directive 2002/46/EC on the approximation of the laws of the Member States relating to food supplements, Article 6. OJ L 183, 12.7.2002, p. 51–57.
5. European Parliament and Council. Regulation (EC) No 1924/2006 on nutrition and health claims made on foods, Annex. OJ L 404, 30.12.2006, p. 9–25.
6. MedlinePlus, U.S. National Library of Medicine. Soluble vs. insoluble fiber. Reviewed 2026.
7. Lambeau KV, McRorie JW Jr. Fiber supplements and clinically proven health benefits: How to recognize and recommend an effective fiber therapy. Journal of the American Association of Nurse Practitioners. 2017;29(4):216–223.
8. European Parliament and Council. Regulation (EU) No 1169/2011 on the provision of food information to consumers, Article 18. OJ L 304, 22.11.2011, p. 18–63.
9. British Dietetic Association. Fibre: Food Fact Sheet. 2021.
10. European Commission. Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children's development and health. OJ L 136, 25.5.2012, p. 1–40.
11. European Medicines Agency (EMA). Community herbal monograph on Plantago ovata Forssk., seminis tegumentum. EMA/HMPC/199774/2012, 2013.
12. NHS. Symptoms of bowel cancer. Reviewed 2026.

The information provided is general in nature and does not replace advice from a doctor or dietitian. The scientific data refer to fibre and nutrition in general and do not describe the properties of any specific product. If you have a long-term condition, take medicines, are pregnant or breastfeeding, talk to a healthcare professional before you start taking food supplements. A food supplement is not a substitute for a varied and balanced diet.