Fibre
Fibre and fibre supplements
This article is written from cited public sources but has not yet been signed off by a qualified expert. Use it as general background only, and check important details with a health professional.
Dietary fibre from whole grains, dals, vegetables, fruits, nuts and seeds supports digestion and is linked with lower risk of several long-term diseases. Most people eat less than recommended. Fibre supplements such as psyllium (isabgol) can help some people but must be taken with enough fluid and can affect how some medicines are absorbed.
What is Fibre and fibre supplements?
Fibre is the part of plant foods that the body cannot fully digest. It is a type of carbohydrate but provides only about half the calories of other carbohydrates.[1]
Soluble fibre attracts water and forms a gel, slowing digestion. Insoluble fibre adds bulk to stool and helps food move through the gut. Most high-fibre foods contain both.[1]
Fibre supplements, such as psyllium husk (isabgol), are concentrated sources of fibre sold as powders, granules or capsules.[2]
Its role in the body
Important food sources
- Whole grains such as whole-wheat atta (roti), brown rice, oats, jowar, bajra and ragiChoose whole-grain over refined versions.
- Dals, rajma, chana, lobia and other pulsesGood sources of soluble fibre.
- Vegetables such as bhindi, beans, peas, carrots and leafy greens
- Fruits such as guava, pear, apple, orange and bananaEating the peel where edible keeps more fibre.
- Nuts and seeds, including flaxseed and almonds
- Psyllium husk (isabgol)A common fibre supplement rich in soluble fibre.
Recommended dietary intake
| Group | Amount | Basis | Region |
|---|---|---|---|
| AdultsWHO 2023 guideline; WHO also recommends at least 400 g of vegetables and fruits a day. | 25 g/day of naturally occurring dietary fibre (at least)[4] | GUIDELINE | WHO |
| Adults (UK)UK government guideline; Indian reference value to be added after verification. | 30 g/day[5] | GUIDELINE | UK |
Signs sometimes associated with low levels
Why symptoms alone cannot confirm a deficiency
Signs like tiredness, weakness, hair fall or low mood are very common and have many possible causes, such as poor sleep, stress, infections, thyroid problems or other illnesses.
The same sign can come from several different nutrients, or from no nutrient problem at all.
Only a qualified clinician, using your history, an examination and, when needed, lab tests, can say whether a deficiency is present. This app cannot diagnose a deficiency from symptoms or from BMI.
Constipation, bloating or changes in bowel habit can come from many causes, including medicines, low fluid intake, thyroid problems and bowel conditions. A change in bowel habit that lasts, blood in the stool or unexplained weight loss needs a doctor’s assessment.
Tests a clinician might consider
- There is no blood test for fibre intake. A dietitian can estimate intake from what you eat. For persistent bowel symptoms, a doctor decides which tests, if any, are needed.[1]
Who is more likely to have low intake
Potential benefits and quality of evidence
- Eating plenty of fibre is associated with a lower risk of heart disease, stroke, type 2 diabetes and bowel cancer.[5] Moderate evidence
- Fibre helps digestion and helps prevent constipation.[1] Established
- Soluble fibre lowers cholesterol.[1] Established
- WHO recommends that carbohydrates come mainly from whole grains, vegetables, fruits and pulses.[4] Established
Side effects
Risks of too much
- Fibre supplements need enough liquid. The psyllium drug information says the powder must be mixed with a full glass (about 240 ml) of liquid and that at least this much liquid is needed for it to work properly and to prevent side effects. It advises calling a doctor immediately for difficulty breathing or swallowing, stomach pain, rash, itching, nausea or vomiting.[3]
- Very high fibre intakes may reduce absorption of minerals such as iron, zinc, magnesium and calcium, although high-fibre foods are usually rich in minerals.[1]
Medicine and supplement interactions
- Digoxin, aspirin (salicylates) and nitrofurantoin: Psyllium should not be taken within 3 hours of these medicines, according to the drug information.[3]
- Other medicines and supplements: Psyllium may change how other medicines are absorbed; tell your doctor and pharmacist about everything you take.[3]
Never start, stop or change a prescribed medicine because of this list — talk to your doctor or pharmacist.
Pregnancy and breastfeeding
- Fibre from food is part of a healthy diet in pregnancy. Before taking a fibre supplement in pregnancy or while breastfeeding, tell your doctor.[3]
Kidney and liver cautions
- The psyllium drug information advises telling your doctor before use if you have kidney disease, diabetes, heart disease, high blood pressure, rectal bleeding, a history of bowel blockage or difficulty swallowing. Some products also contain sugar or sodium.[3]
Upper intake limits
No Tolerable Upper Intake Level is set for dietary fibre in our sources. Supplement labels give use directions; the psyllium drug information advises not to use it for constipation for longer than 1 week unless a doctor advises.[3]
When to talk to a professional
Talk to a doctor or registered dietitian before starting a supplement, especially if you are pregnant or breastfeeding, have a long-term illness, or take any regular medicines.
Do not start, stop or change a prescribed medicine because of anything you read here.
Supplements sold without a prescription are not automatically safe. Doses, quality and interactions still matter.
Seek medical care promptly if you have severe, sudden or worsening symptoms.
If you have had bowel surgery, a bowel narrowing, or difficulty swallowing, ask your doctor before using fibre supplements.
A change in bowel habit lasting more than a few weeks should be checked by a doctor rather than treated with supplements alone.
Still being verified
- ICMR-NIN fibre guidance not verified; not stated.
- US fibre Adequate Intake values (US Food and Nutrition Board) not verified against a primary source in this pass; MedlinePlus gives a general 21–38 g/day range for older children, adolescents and adults.
References
- MedlinePlus (US National Library of Medicine), content by A.D.A.M.. Fiber — MedlinePlus Medical Encyclopedia (opens in a new tab) (2026-07-22). Accessed 9 Oct 2026.
- MedlinePlus (US National Library of Medicine), content by A.D.A.M.. Soluble vs. insoluble fiber — MedlinePlus Medical Encyclopedia (opens in a new tab) (2026-08-25). Accessed 9 Oct 2026.
- MedlinePlus (US National Library of Medicine), content from AHFS. Psyllium — MedlinePlus Drug Information (opens in a new tab) (2024-06-20). Accessed 9 Oct 2026.
- World Health Organization. WHO updates guidelines on fats and carbohydrates (news release) (opens in a new tab) (2023-07-17). Accessed 9 Oct 2026.
- NHS (England). How to get more fibre into your diet (opens in a new tab) (2026-03-02). Accessed 9 Oct 2026.
Sources checked: 9 Oct 2026
This page is general education, not personal medical advice. For diagnosis, treatment or medicines, please talk to a qualified doctor, registered dietitian or pharmacist. Read our medical & AI disclaimer.