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Nutrients

Dietary fibre

Dietary fibre is a diverse group of mainly non-digestible carbohydrates. You find it predominantly in wholegrains, pulses, vegetables, fruit, nuts and seeds.

Nutrient1 authorised EU claim28 sources

Dietary fibre is not a single substance but a group of food components that are neither digested nor absorbed in the human small intestine. Examples include cellulose, pectins, beta-glucans, inulin and resistant starch. EFSA's nutritional definition also includes associated lignin, which is not a carbohydrate. EU food labelling uses a specific definition: fibre consists of carbohydrate polymers with at least three monomeric units. These may occur naturally in foods, be obtained from food raw materials or be manufactured synthetically. For extracted and synthetic forms, a beneficial physiological effect must be demonstrated by generally accepted scientific evidence. Fibre is often divided into soluble and insoluble types. Its viscosity and its fermentability by gut microorganisms also vary, so different fibres do not necessarily have the same effects. Eating a variety of plant foods provides different fibre types; isolated fibres can also be added to foods as ingredients.

What is dietary fibre?

Dietary fibre is a group of food components that are neither digested nor absorbed in your small intestine. Examples include cellulose, pectins, beta-glucans, inulin and resistant starch. Most are carbohydrates; EFSA's nutritional definition also includes associated lignin, which is not a carbohydrate.

Not all fibres have the same effects

Fibre is often divided into soluble and insoluble types. Fibres also differ in how they hold water, form viscous solutions or gels, and are fermented by gut microorganisms. Solubility alone therefore does not reliably predict a particular fibre's effects in the body.

Dietary fibre supports normal bowel function and normal bowel movements. Effects also depend on fibre type: findings for one fibre cannot automatically be applied to all others.

Finding fibre in everyday foods

Fibre is found predominantly in wholegrain foods, pulses, vegetables, fruit, nuts and seeds. Eating a variety of plant foods provides different types of fibre. Isolated fibres can also be added to foods as ingredients.

If you currently eat little wholegrain food, increase it gradually and drink enough fluids. Fibre supplements can cause gas and abdominal discomfort. Tolerance depends on fibre type, amount and individual sensitivity; gradual increases are particularly useful if you have irritable bowel syndrome.

What does ‘high fibre’ mean on a label?

Under Regulation (EC) No 1924/2006, a food may be described as a ‘source of fibre’ if it contains at least 3 g of fibre per 100 g or 1.5 g per 100 kcal. ‘High fibre’ requires at least 6 g per 100 g or 3 g per 100 kcal.

These are nutrition claims about composition, not health claims. EFSA's recommendation of 25 g daily is not an authorised generic EU health claim for every fibre product either.

How nutrition works

  • Evidence: strong

    Bowel regularity

    • An adequate dietary fibre intake supports normal bowel function. [1]

      Evidence

  • Evidence: strong

    Glycaemic control

    • Beta-glucans from oats or barley contribute to reducing the rise in blood glucose after a meal. [2][3]

      Authorised EU claim

  • Evidence: strong

    Blood pressure

    • Higher fibre intake can lower systolic and diastolic blood pressure in adults with hypertension. [4]

      Evidence

  • Evidence: moderate

    Body weight

    • Viscous fibre supplements may produce a small reduction in body weight without prescribed energy restriction. [5]

      Evidence

Statements & evidence

  • Dietary fibre is a diverse group of food components that are not digested in the human small intestine. [6]

    EFSA includes non-digestible carbohydrates and lignin in its definition. Fibre is therefore not a single substance with uniform properties.

    Nutrition factEvidence: strong

  • Fibres differ in how they hold water, form gels and are fermented by gut bacteria. [6][7]

    The distinction between soluble and insoluble fibre alone does not reliably predict a particular fibre’s physiological effects. Findings for one fibre cannot automatically be applied to all fibres.

    EvidenceEvidence: strong

  • Sources of dietary fibre include wholegrain foods, pulses, fruit, vegetables, nuts and seeds. [8]

    These food groups provide different types of fibre. This is a qualitative description of sources, not a statement that every food in these groups meets the legal conditions for a ‘high fibre’ claim.

    Nutrition factEvidence: strong

  • EFSA sets an adequate intake of 25 g of dietary fibre per day for adults. [6]

    This is a dietary reference value, not an authorised EU health claim or an upper intake limit. National recommendations may differ.

    Nutrition factEvidence: strong

  • For EU nutrition labelling, fibre is included in energy calculations using 8 kJ or 2 kcal per gram. [9]

    This is a regulatory conversion factor. It does not mean that every type of fibre provides exactly the same amount of energy in the body.

    Nutrition factEvidence: strong

  • ‘Source of fibre’ requires at least 3 g of fibre per 100 g or 1.5 g per 100 kcal. ‘High fibre’ requires at least 6 g per 100 g or 3 g per 100 kcal. [10]

    These are nutrition claims under EU law, not health claims. The thresholds describe a food’s composition, not a particular health effect.

    Nutrition factEvidence: strong

  • If you currently eat little wholegrain food, DGE recommends increasing it gradually and drinking enough fluids. [11]

    This is practical guidance for changing your diet. It does not replace product-specific instructions for concentrated fibre supplements.

    Nutrition factEvidence: moderate

Safety information

  • Upper level

    No established upper intake limit

    No tolerable upper intake level has been established for dietary fibre. EFSA's adequate intake of 25 g daily for adults is not an upper limit. The absence of a limit does not mean that unlimited intake or every supplement dose is safe. [12][6]

  • Side effect · Adults

    Gas and abdominal discomfort

    Fibre supplements can cause gas and abdominal discomfort. Increase your fibre intake gradually, especially if you have IBS. Tolerance depends on fibre type, amount and individual sensitivity. [13][14]

  • Caution

    Swelling supplements need sufficient fluid

    Take psyllium or glucomannan products with the amount of fluid required by their instructions, not dry. Insufficient fluid can cause choking or blockage of the oesophagus or intestine. Seek immediate medical help for chest pain, vomiting, or difficulty swallowing or breathing after taking them. This warning concerns swelling products, not ordinary fibre-containing foods. [15][16]

  • Side effect

    Allergic reactions to psyllium

    Psyllium can cause allergic reactions, including anaphylaxis; their frequency is unknown. Avoid inhaling the powder, especially if you regularly prepare it for others. Seek emergency help for breathing difficulty or swelling of the mouth or throat. [15]

  • Interaction

    Check spacing from medicines

    Psyllium can delay the absorption of certain medicines, including lithium, carbamazepine, cardiac glycosides and coumarin anticoagulants. Ask a pharmacist about the appropriate interval and follow both products' instructions. Glucomannan also requires spacing; there is no single interval suitable for all products and medicines. [15][17][16]

  • Interaction

    Review diabetes and thyroid treatment

    If you take diabetes medicines or thyroid hormones, check with your clinician before starting a psyllium product. Treatment may need additional monitoring or dose adjustment. Do not change your medicine dose yourself. [15]

  • Interaction

    Caution with medicines that slow the bowel

    Do not combine psyllium with medicines that slow bowel movement, such as opioids including codeine, without medical supervision. This combination can increase the risk of bowel blockage. [15][17]

  • Contraindication

    Psyllium is not suitable for everyone

    Do not use ispaghula medicines if you have known or suspected bowel obstruction, narrowing of the digestive tract, intestinal paralysis, megacolon, swallowing or throat problems, or an allergy to the product. These contraindications are not a blanket ban on fibre-containing foods. [15]

  • Caution

    Have unexplained bowel symptoms assessed first

    Seek medical advice before using an ispaghula medicine if you have an unexplained change in bowel habits lasting more than two weeks, unexplained rectal bleeding, or no bowel movement after a laxative. Suspected faecal impaction with abdominal pain, nausea or vomiting also needs assessment first. [15]

  • Caution

    Choose supplements carefully during pregnancy and breastfeeding

    Ispaghula may be considered during pregnancy and breastfeeding when needed if dietary changes have not helped enough, although pregnancy-outcome data are limited. This does not automatically apply to every fibre supplement. Seek clinical advice before using glucomannan. [15][16]

  • Caution

    Age restrictions for ispaghula medicines

    EMA does not recommend ispaghula medicines for constipation below age 6, or for increasing fibre intake below age 12, because efficacy data are insufficient. Follow the individual product's age instructions. These restrictions concern medicines, not fibre in ordinary foods. [15]

  • Caution

    Medical supervision for older or debilitated people

    Ispaghula treatment in older or physically debilitated people should be medically supervised. This is not a general recommendation to avoid fibre-containing foods. [15]

  • Caution

    Individualise fibre intake with bowel narrowing

    If you have bowel narrowing or an increased risk of obstruction, the amount of fibre and the texture of your foods may need adjustment. Seek medical or dietetic guidance. A strict low-fibre diet is not necessary for every stricture. [18]

Found in

Frequently asked questions

What is dietary fibre?

Dietary fibre is a group of food components that are not digested in the small intestine, such as cellulose, pectins and resistant starch. Their properties differ, so not all fibres have the same effects.

How much fibre do I need each day?

EFSA sets an adequate intake of 25 g of fibre per day for adults, based on normal bowel function. This is not an upper intake limit, and national recommendations may differ.

Which foods provide fibre?

Fibre is found predominantly in wholegrain foods, pulses, vegetables, fruit, nuts and seeds. Eating a variety of plant foods provides different types of fibre.

Does fibre help keep bowel movements regular?

Dietary fibre supports normal bowel function and normal bowel movements. Effects also depend on fibre type, so findings for one fibre cannot automatically be applied to all others.

Can fibre cause gas or bloating?

Fibre supplements can cause gas and abdominal discomfort; tolerance depends on fibre type, amount and individual sensitivity. Increase your fibre intake gradually, especially if you have irritable bowel syndrome.

Sources

  1. 01European Food Safety Authority · 2010EFSA sets European dietary reference values for nutrient intakesOpen source
  2. 02European Commission · 2012Commission 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 healthOpen source
  3. 03EFSA Journal · 2025Beta-glucans from oats or barley and reduction of postprandial glycaemic responses: Modification of an authorised health claimDOI 10.2903/j.efsa.2025.9630
  4. 042022Dietary fibre in hypertension and cardiovascular disease management: systematic review and meta-analysesOpen source
  5. 05The American Journal of Clinical Nutrition · 2020Can dietary viscous fiber affect body weight independently of an energy-restrictive diet? A systematic review and meta-analysis of randomized controlled trialsOpen source
  6. 06EFSA Journal · 2010Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibreDOI 10.2903/j.efsa.2010.1462
  7. 07EFSA Journal · 2010Scientific Opinion on the substantiation of health claims related to dietary fibre (ID 744, 745, 746, 748, 749, 753, 803, 810, 855, 1415, 1416, 4308, 4330) pursuant to Article 13(1) of Regulation (EC) No 1924/2006DOI 10.2903/j.efsa.2010.1735
  8. 08European Food Safety Authority · 2021Dietary fibre — presentation to the 118th plenary meeting of the NDA PanelOpen source
  9. 09European Parliament and Council of the European Union · 2011Regulation (EU) No 1169/2011 on the provision of food information to consumersOpen source
  10. 10European CommissionNutrition claimsOpen source
  11. 11Deutsche Gesellschaft für ErnährungGetreide, Getreideprodukte und KartoffelnOpen source
  12. 12EFSA Journal · 2025Safety of the extension of use of galacto-oligosaccharides as a novel food pursuant to Regulation (EU) 2015/2283DOI 10.2903/j.efsa.2025.9797
  13. 13The American Journal of Clinical Nutrition · 2022The Effect of Fiber Supplementation on Chronic Constipation in Adults: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trialsvan der Schoot A, Drysdale C, Whelan K, Dimidi EDOI 10.1093/ajcn/nqac184PubMed 35816465
  14. 14National Institute of Diabetes and Digestive and Kidney DiseasesEating, Diet, & Nutrition for Irritable Bowel SyndromeOpen source
  15. 15European Medicines AgencyCommunity herbal monograph on Plantago ovata Forssk., seminis tegumentumOpen source
  16. 16Health CanadaGlucomannan monographOpen source
  17. 17NHSTaking Fybogel with other medicines and herbal supplementsOpen source
  18. 18Royal Free London NHS Foundation TrustLow fibre dietOpen source
  19. 19U.S. Department of Agriculture, Agricultural Research Service – FoodData Central · 2019Bananas, raw (FDC ID 173944, SR Legacy)Open source
  20. 20Deutsche Gesellschaft für ErnährungAusgewählte Fragen und Antworten zu BallaststoffenOpen source
  21. 212019Carbohydrate quality and human health: a series of systematic reviews and meta-analysesPubMed 30638909Open source
  22. 22European Commission · 2015Commission Regulation (EU) 2015/2314 amending Regulation (EU) No 432/2012Open source
  23. 23European Commission · 2025Consolidated text of Commission Regulation (EU) No 432/2012, 20 August 2025Open source
  24. 242018Dietary fiber intervention on gut microbiota composition in healthy adults: a systematic review and meta-analysisPubMed 29757343Open source
  25. 25PLOS Medicine · 2020Dietary fibre and whole grains in diabetes management: Systematic review and meta-analysesDOI 10.1371/journal.pmed.1003053
  26. 26EFSA Journal · 2011Scientific Opinion on the substantiation of health claims related to oat and barley grain fibre and increase in faecal bulk (ID 819, 822) pursuant to Article 13(1) of Regulation (EC) No 1924/2006DOI 10.2903/j.efsa.2011.2249
  27. 272019Should Viscous Fiber Supplements Be Considered in Diabetes Control? Results From a Systematic Review and Meta-analysis of Randomized Controlled TrialsPubMed 30617143Open source
  28. 282023Soluble Fiber Supplementation and Serum Lipid Profile: A Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled TrialsPubMed 36796439Open source