Fibre supplements compared

Q: Which fibre supplement is best?

The sources read do not name a winner. Psyllium has the most trial evidence for constipation and cholesterol. No trial compared all five fibres.

Q: Does psyllium help constipation?

Yes, probably. In a 2022 meta-analysis of 16 trials, 66% of people on fibre responded versus 41% on control. The trials differed a lot, and gas was more common.

Q: Is methylcellulose better than psyllium?

Not shown. A small 2026 scan study in 22 healthy people found methylcellulose made more bowel water than psyllium. A 1988 study found both raised stool frequency in constipated people but did not show one beat the other.

Q: Does calcium polycarbophil work?

A review in older adults found it better than placebo for short-term constipation, and a small 1993 trial found 15 of 21 people with irritable bowel syndrome preferred it to placebo. The studies are small and old.

Q: Is inulin a laxative?

Reviews say it is not, because gut bacteria ferment it. A pooled analysis found it raised Bifidobacterium and helped bowel function in healthy people. Evidence for constipation was not found.

Q: Does wheat dextrin help constipation?

No trial of wheat dextrin alone was found. One small trial of a blend that included it helped, but the blend cannot be credited to wheat dextrin. A 2017 review says it is not a laxative.

Q: Does psyllium lower cholesterol?

Modestly. Two meta-analyses found LDL cholesterol lower by about 0.33 to 0.35 mmol/L. That is a lab marker, not proof of fewer heart attacks, and it is a psyllium result.

Q: Does fibre help irritable bowel syndrome?

A little, mainly soluble fibre such as psyllium or calcium polycarbophil, and mostly in IBS with constipation. It did not help abdominal pain, and bran did not help.

Q: Why must dry fibre be taken with fluid?

Swelling fibres can block the throat or gullet if taken without enough fluid. A US federal rule requires a Choking warning and a direction to use a full glass of fluid, and says people with trouble swallowing should not take them.

Q: Can fibre supplements affect my medicines?

They can. MedlinePlus lists digoxin, aspirin and nitrofurantoin for psyllium, and a review found limited evidence for levothyroxine. Ask a pharmacist about your own medicines.

Plantago ovata (psyllium), methylcellulose, calcium polycarbophil, inulin, wheat dextrin · also called Bulk-forming laxatives, ispaghula, fibra en suplementos

Fibre supplements add bulk or feed gut bacteria. Psyllium has the best evidence: it helps chronic constipation and lowers LDL cholesterol a little. Methylcellulose and calcium polycarbophil have only small, older studies, and inulin and wheat dextrin are not shown to ease constipation. Swelling fibres can block the throat or bowel if taken without enough fluid, so ask a doctor or pharmacist first.

General information, not medical advice. Last substantive update October 26, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

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About Fibre supplements compared

Fibre supplements are not all alike. Psyllium forms a thick gel and has the best evidence for constipation and cholesterol. Methylcellulose and calcium polycarbophil are also bulk-forming but have little recent evidence. Inulin and wheat dextrin are fermented by gut bacteria and are not shown to relieve constipation. No trial compared all five.

What these fibres are

Three of the five (psyllium, methylcellulose and calcium polycarbophil) are named together in a US federal labelling rule for swelling gums and mucilloids that are sold as over-the-counter bulk-forming laxatives. Inulin (from chicory) and wheat dextrin are fermented by gut bacteria and are usually sold as foods or supplements.

This page compares what is documented about each. It does not rank products or name a winner, and none of the sources read did either.

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Two things that explain most differences

Reviewers sort fibres by how thick a gel they make and whether gut bacteria ferment them. In two narrative reviews with the same lead author, psyllium is a thick, unfermented gel that holds water through the large bowel, while inulin and wheat dextrin are fermented, non-viscous fibres that do not act as laxatives and, in the case of wheat dextrin, may even be constipating.

That is the reviewers' interpretation, not a trial result. A small 2026 scan study in healthy people found that methylcellulose made more bowel water than psyllium and that both gels reduced gas after inulin.

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Where the fibres come from

Psyllium is the seed husk of Plantago ovata, and inulin in the pooled analysis came from chicory. One blend trial used resistant dextrin made from wheat starch. Methylcellulose is a modified cellulose widely used in food manufacture.

The amounts of fibre in everyday foods were not read from USDA or NIH pages for this page, so none are given. Fibre in foods comes with other nutrients and is not the same as these supplements.

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What the research shows

The best evidence is for psyllium: a 2022 meta-analysis of 16 trials found 66% of people on fibre responded versus 41% on control in chronic constipation (moderate certainty), and two meta-analyses found modest LDL cholesterol lowering. Methylcellulose and calcium polycarbophil have small and older trials. Inulin raises Bifidobacterium bacteria but is not shown to relieve constipation. Wheat dextrin alone has no trial; one blend helped in 54 adults.

In irritable bowel syndrome, soluble fibre helped a little and bran did not. Psyllium lowered blood sugar markers in type 2 diabetes and cut episodes of fecal incontinence in one trial. In 13 people after pouch surgery, methylcellulose made no difference.

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Choking, blockage, allergy and medicine timing

A US federal rule says choking and gullet blockage have been linked to these swelling fibres taken without enough fluid, and requires a Choking warning and a direction to use a full glass of fluid on dry forms. People with trouble swallowing should not take them. Case reports describe gullet and bowel blockage with psyllium. Psyllium can also cause allergy, including from breathing in the powder.

Fibre can change how some medicines are absorbed: MedlinePlus lists digoxin, aspirin and nitrofurantoin for psyllium, and a review found limited evidence for levothyroxine. Gas and bloating are the common problem. This is a regulator and source summary, not advice to take or avoid any product.

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Where evidence is missing

No trial compared all five fibres, and none showed one beating the others for symptoms. A fibre that has not been studied is not proven useless, and one that has been studied is not proven best. If you wonder which suits you, ask a doctor, pharmacist or dietitian.

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At a glance

Traditional uses history, not proof

Fibre from food is part of normal digestion
Sold as powders, caplets, capsules and wafers for regularity and gut comfort

Studied for research

Chronic constipation (mostly psyllium), moderate certainty
LDL cholesterol (psyllium), moderate certainty
Methylcellulose and calcium polycarbophil for constipation, low certainty
Irritable bowel syndrome, low certainty
Blood sugar markers (psyllium) and fecal incontinence (psyllium), low certainty
Inulin and gut bacteria, low certainty
Wheat dextrin alone, insufficient evidence

Main compounds

Psyllium husk (gel-forming)
Methylcellulose (gelling)
Calcium polycarbophil (bulk-forming)
Inulin (fermented)
Wheat dextrin (fermented)

Common forms

Powders and granules mixed with fluid
Caplets, capsules and wafers
Blends with several fibres

Research links: 2022 meta-analysis: fibre for chronic constipation (16 trials) · 2018 meta-analysis: psyllium and LDL cholesterol (28 trials) · 2021 review: constipation treatments in people over 65 · 1988 study: methylcellulose as a bulk laxative · US labelling rule for swelling fibres (21 CFR 201.319) · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Fibre supplements: bulk-forming fibres (psyllium, methylcellulose, calcium polycarbophil) and fermentable fibres (inulin, wheat dextrin)
Common names: Fibre supplements (English); Bulk-forming laxatives (English); Fibra dietética en suplementos (Spanish); Laxantes formadores de masa (Spanish)
Family or group: Dietary fibre. The 2016 and 2017 reviews sort fibres by two traits: gel thickness (viscosity) and whether gut bacteria ferment them.
Harvest and processing: Psyllium is the seed husk of a plant; chicory is the source named for inulin in the 2023 review; the 2026 blend trial names resistant dextrin from wheat starch. Methylcellulose is described in a 2026 trial abstract as a non-fermentable gelling agent widely used in food manufacture. Further source detail was not read.
Look-alikes and adulterants: Name: Carboxymethylcellulose; Note: A different cellulose gel fibre tested in the fecal incontinence trial. It is not methylcellulose.; Name: Psyllium husk as a herb; Note: Has its own page under Herbs & Botanicals.
Sustainability and conservation: Not assessed.

What is inside, and how it may work

What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Psyllium (ispaghula husk)	gel-forming, not fermented (per reviews)	Not read from a source.	Largest body of trial evidence on this page: constipation, cholesterol, blood sugar markers and fecal incontinence. ^{33 12 4}	Human data
Methylcellulose	cellulose derivative, gelling	Not read from a source.	Called a non-fermentable gelling agent; raised stool water in a 1988 trial; made more bowel water than psyllium on scans in 22 healthy people. ^{10 6}	Human data
Calcium polycarbophil	synthetic bulk-forming polymer with calcium	Not read from a source.	Listed with psyllium and methylcellulose in the US labelling rule. Better than placebo in short-term constipation in a review of older adults; preferred to placebo by 15 of 21 people with IBS in a 1993 trial. ^{28 13 24}	Human data
Inulin (chicory)	fermentable fructan	Not read from a source.	Raises Bifidobacterium in pooled trials; reviews say it does not act as a laxative. ^{18 15}	Human data
Wheat dextrin	soluble, non-viscous, fermentable fibre (per reviews)	Not read from a source.	No trial of wheat dextrin alone was found; one blend trial helped constipation. ^{7 16}	Human data

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Water holding and gel in the large bowel	Not applicable	Reviews by McRorie and colleagues say a laxative fibre must resist fermentation and hold water as a gel through the large bowel; psyllium does and inulin and wheat dextrin do not. ^{15 16}	Expert review
Fermentation by gut bacteria	Not applicable	Inulin is fermented and raises Bifidobacterium. Whether this brings a health benefit was not shown in the abstract. ¹⁸	Human data
Gel in stool	Not applicable	In the fecal incontinence trial only psyllium formed a gel in stool, and psyllium alone cut episodes. ⁴	Human data

Absorption, metabolism and elimination

Absorption: LactMed says psyllium is not absorbed from the gut. Absorption of the other four was not read.
Distribution: Not read.
Metabolism: Fermentable fibres are fermented by gut bacteria (inulin review). Not read for others.
Elimination: Not read in detail.

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Isolated compounds versus whole extracts

These are isolated fibres sold as powders, caplets or wafers. Fibre in foods comes with other nutrients and is not the same as these supplements. No trial in the sources read compared food fibre with these supplements, and food fibre amounts were not read from USDA or NIH pages.

Nutritional composition

Food sources of fibre and amounts per portion were not read from USDA or NIH pages for this page, so none are stated. Sources named in the studies: seed husk of Plantago ovata (psyllium), chicory (inulin), wheat starch (resistant wheat dextrin).

12benefits and uses looked at

33studies and sources checked

Moderate certaintybest evidence rating found

5lab markers tracked in trials

2 moderate certainty7 low certainty2 very low certainty1 not enough evidence

What was looked at

The 12 benefits and uses checked for Fibre supplements compared, each with how strong the evidence is. Tap one to open it.

Constipation (fibre supplements, mostly psyllium)Moderate certainty
Methylcellulose and calcium polycarbophil for constipationLow certainty
Cholesterol (psyllium)Moderate certainty
Why the five fibres behave differentlyLow certainty
Irritable bowel syndrome (IBS)Low certainty
Inulin: gut bacteria and bowel function in healthy peopleLow certainty
Methylcellulose and psyllium gels and gas from inulinVery low certainty
Wheat dextrin (in a blend) and functional constipationNot enough evidence
Fecal incontinence (leaking loose stool)Low certainty
Blood sugar (psyllium)Low certainty
Extra LDL lowering when added to statins (psyllium)Low certainty
After pouch surgery for ulcerative colitis (methylcellulose)Very low certainty

Lab markers tracked in the studies

Response to treatment in chronic constipationLDL cholesterolFasting glucose and HbA1cBifidobacterium abundanceEpisodes of fecal incontinence per week

What is Fibre supplements compared good for?

The main studied uses and how strong the human evidence is for each. Most results are for psyllium. They do not carry over automatically to the other fibres.

Constipation (fibre supplements, mostly psyllium)Moderate certaintyIn adults with long-term constipation, fibre supplements helped in pooled trials. Psyllium has the most evidence and was graded moderate in an over-the-counter review. Gas was more common. The best evidence is for psyllium; it does not carry over automatically to the other fibres. Methylcellulose and calcium polycarbophil for constipationLow certaintyMethylcellulose and calcium polycarbophil are sold as bulk-forming laxatives, but the trials we could read are old and small. A 1988 study found methylcellulose raised stool frequency and stool water. A review in older adults found calcium polycarbophil better than placebo in the short term. We found no trial that compared them head to head with psyllium. Cholesterol (psyllium)Moderate certaintyPsyllium taken regularly lowered LDL ('bad') cholesterol modestly in pooled trials. This is a lab marker, not proof of fewer heart attacks. The evidence is for psyllium; the sources read say non-gel fibres such as inulin and wheat dextrin do not share this effect. Why the five fibres behave differentlyLow certaintyTwo reviews with the same lead author say two traits explain most differences: how thick a gel the fibre makes, and whether gut bacteria ferment it. By their account, psyllium is a thick, unfermented gel and helps constipation and cholesterol, while inulin and wheat dextrin are readily fermented, non-viscous fibres that do not act as laxatives. Irritable bowel syndrome (IBS)Low certaintyFibre helped IBS symptoms a little in pooled trials, mainly soluble fibre (psyllium, ispaghula, calcium polycarbophil). It did not help abdominal pain. A small 1993 trial found most people with IBS preferred calcium polycarbophil to placebo. Insoluble fibre such as bran did not help. Inulin: gut bacteria and bowel function in healthy peopleLow certaintyInulin from chicory raised Bifidobacterium (a gut bacterium) in a pooled analysis of 50 studies and helped bowel function in healthy people. A 2016 expert review says inulin does not act as a laxative, and evidence for constipation relief was not found in the sources read. More Bifidobacterium is a bacteria count, not a symptom result. Methylcellulose and psyllium gels and gas from inulinVery low certaintyA small 2026 trial in 22 healthy volunteers tested whether gels of methylcellulose or psyllium cut gas after inulin. Both were linked to less gas in the colon once they arrived there, and methylcellulose added more water than psyllium. This is a scan study in healthy people, not proof of symptom relief. Wheat dextrin (in a blend) and functional constipationNot enough evidenceWe found no trial of wheat dextrin on its own. In one 2026 trial of 54 adults, a blend of resistant wheat dextrin, pectin, citrus fibre and oat fibre raised bowel movements versus placebo. The blend cannot be credited to wheat dextrin alone. A 2017 review says wheat dextrin is not a laxative and may be constipating. Fecal incontinence (leaking loose stool)Low certaintyIn 189 adults with fecal incontinence, psyllium cut episodes of leaking loose stool versus placebo, while carboxymethylcellulose (another gel fibre) made them worse and gum arabic did not clearly help. Only psyllium formed a gel in the stool. Symptoms with fibre were mild. Blood sugar (psyllium)Low certaintyIn people with type 2 diabetes, psyllium lowered fasting glucose and HbA1c in pooled trials. The results are lab markers and the main meta-analysis has authors from a psyllium maker. People on diabetes medicines should talk to their doctor first. Extra LDL lowering when added to statins (psyllium)Low certaintyIn three trials in people already on statins, adding psyllium lowered LDL more than the statin alone. The authors, who worked for a psyllium maker, said the extra drop was like doubling the statin. It is a small pool of trials. After pouch surgery for ulcerative colitis (methylcellulose)Very low certaintyIn a small crossover study of 13 people after pouch surgery, methylcellulose (Citrucel) did not change stool frequency, pouch function, bloating, stool form or continence. The authors saw little role for fibre supplements there. This is a very small, specialised group.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Constipation (fibre supplements, mostly psyllium)

Moderate certainty

In adults with long-term constipation, fibre supplements helped in pooled trials. Psyllium has the most evidence and was graded moderate in an over-the-counter review. Gas was more common. The best evidence is for psyllium; it does not carry over automatically to the other fibres.

3 studiesMostly psyllium husk; the meta-analysis pooled several fibre types. C…

Studies, doses and limits

What the trials found

A 2022 meta-analysis of 16 randomised trials (1,251 adults) found that 66% of people on fibre responded versus 41% on control (RR 1.48). Stool frequency and stool softness improved, and flatulence was higher with fibre. The trials differed a lot and covered several fibre types. A 2021 review of 41 trials of over-the-counter products graded psyllium as moderate evidence (grade B); polyethylene glycol and senna were graded higher. That review was funded by Bayer US. A 2021 review of 23 trials in people over 65 found psyllium and calcium polycarbophil better than placebo in the short term, with small, lower-quality trials.

Results

Fibre supplements probably help chronic constipation in adults, with psyllium best supported. How big the help is for any one person is unknown.

Effect sizes as reported

Responders RR 1.48 (fibre versus control); stool frequency SMD 0.72; stool consistency SMD 0.32; flatulence SMD 0.80. Responders 311 of 473 on fibre versus 134 of 329 on control.

Why this rating

Moderate for psyllium (grade B in the over-the-counter review, a large meta-analysis). Large differences between trials, and the over-the-counter review was industry-funded.

Form and dose studied

Mostly psyllium husk; the meta-analysis pooled several fibre types. Calcium polycarbophil is covered in the next item.

Who was studied

Adults with chronic constipation; a separate review covers people over 65.

Limits

The trials were very different from each other. Most were short. Pooled results blend several fibres.

Why researchers looked

Constipation is common, and bulk-forming fibre is a standard first step, so many trials have tested it.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Reviewer interpretation

Psyllium absorbs water and stays as a gel through the large bowel, so stool is softer and bulkier. This is described by the authors of reviews; it is not proven for every fibre.

A proposed mechanism does not show that the effect happens in people.

Gas and bloating were more common. Choking and blockage cautions apply; see Safety.

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Methylcellulose and calcium polycarbophil for constipation

Low certainty

Methylcellulose and calcium polycarbophil are sold as bulk-forming laxatives, but the trials we could read are old and small. A 1988 study found methylcellulose raised stool frequency and stool water. A review in older adults found calcium polycarbophil better than placebo in the short term. We found no trial that compared them head to head with psyllium.

2 studiesMethylcellulose and calcium polycarbophil as bulk laxatives; amounts …

Studies, doses and limits

What the trials found

In a 1988 study, 50 healthy people given methylcellulose had more frequent stools with more water and solids. In 59 constipated people, methylcellulose (three amounts) and psyllium each raised stool frequency, water and solids. The abstract gives no numbers and does not show one fibre beating the other. A 2021 systematic review of 23 trials in people over 65 listed calcium polycarbophil among laxatives that beat placebo in the short term, with small trials of limited quality. In a 13-person crossover study after pouch surgery, methylcellulose made no difference.

Results

Some evidence that both ease constipation, but it is thin, old and small. No head-to-head result.

Effect sizes as reported

No pooled numbers. Methylcellulose 1988: significant rises in stool frequency, water and solids (numbers not in the abstract).

Why this rating

Low. Small and old studies; the review does not single out polycarbophil; no comparison with psyllium.

Form and dose studied

Methylcellulose and calcium polycarbophil as bulk laxatives; amounts used in trials are in the studies table only.

Who was studied

Healthy adults and constipated adults (1988 study); people over 65 (review).

Limits

Old studies; abstracts give no numbers; the review does not give a result for calcium polycarbophil alone.

Why researchers looked

Both are on the same US laxative labelling rule as psyllium, so people ask whether they work the same way.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Not established

Both are described as bulk-forming, water-holding fibres. The sources read do not test how this works in the body.

A proposed mechanism does not show that the effect happens in people.

Same choking and blockage cautions as other bulk-forming fibres; see Safety.

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Cholesterol (psyllium)

Moderate certainty

Psyllium taken regularly lowered LDL ('bad') cholesterol modestly in pooled trials. This is a lab marker, not proof of fewer heart attacks. The evidence is for psyllium; the sources read say non-gel fibres such as inulin and wheat dextrin do not share this effect.

3 studiesPsyllium husk only.

Studies, doses and limits

What the trials found

A 2018 meta-analysis of 28 randomised trials (1,924 people, trials of 3 weeks or longer) found psyllium lowered LDL by 0.33 mmol/L, non-HDL cholesterol by 0.39 mmol/L and apolipoprotein B by 0.05 g/L. GRADE quality was moderate for LDL and non-HDL (reduced for inconsistency) and high for apoB. A 2024 meta-analysis of 29 trials (2,769 adults) found total cholesterol down 0.28 mmol/L and LDL down 0.35 mmol/L, with no clear change in HDL or triglycerides. The authors of that review modelled about a 7% lower cardiovascular event risk; that is an estimate, not a trial result.

Results

A real but modest lowering of LDL and total cholesterol with psyllium. No result for methylcellulose, polycarbophil, inulin or wheat dextrin was read.

Effect sizes as reported

LDL MD -0.33 mmol/L; non-HDL -0.39 mmol/L; apoB -0.05 g/L (2018). Total cholesterol -0.28 mmol/L; LDL -0.35 mmol/L (2024).

Why this rating

Moderate (GRADE) for LDL, from two meta-analyses; the effect is on a lab marker, not on heart attacks.

Form and dose studied

Psyllium husk only.

Who was studied

Adults with and without high cholesterol.

Limits

Lab-marker result; trials differed; abstract-only read; the 7% risk figure is a model.

Why researchers looked

Gel-forming fibre can bind bile acids and slow fat uptake in the gut, so researchers tested it on cholesterol.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Reviewer interpretation

Authors of reviews link the effect to how thick the fibre gel is in the small bowel. This is an explanation from reviews, not a finding of these trials.

A proposed mechanism does not show that the effect happens in people.

Same choking and blockage cautions; see Safety.

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Why the five fibres behave differently

Low certainty

Two reviews with the same lead author say two traits explain most differences: how thick a gel the fibre makes, and whether gut bacteria ferment it. By their account, psyllium is a thick, unfermented gel and helps constipation and cholesterol, while inulin and wheat dextrin are readily fermented, non-viscous fibres that do not act as laxatives.

3 studiesAll five fibres are discussed; no product is compared.

Studies, doses and limits

What the trials found

Two narrative reviews (2016 and 2017) with the same lead author say a fibre must resist fermentation and hold water through the large bowel to be a laxative. They list psyllium as meeting this and inulin and wheat dextrin as not, and say some fibres, including wheat dextrin, can be constipating. In a 2014 trial in people with fecal incontinence, only psyllium formed a gel in stool, and psyllium cut incontinence episodes while carboxymethylcellulose raised them. These are narrative reviews, so they are less reliable than pooled trials.

Results

A useful way to understand the differences, but it rests on expert reviews rather than head-to-head trials of all five.

Effect sizes as reported

No numbers in the reviews' abstracts.

Why this rating

Low. Narrative reviews with the same lead author; their funding was not stated in the abstracts and was not checked.

Form and dose studied

All five fibres are discussed; no product is compared.

Who was studied

General adults.

Limits

Interpretation by authors; no trial compared all five fibres.

Why researchers looked

People ask which fibre is 'best'; the sources read do not name a winner but do explain how the fibres differ.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Reviewer interpretation

Authors say fermented fibres are used up by gut bacteria before they can hold water in stool, whereas a non-fermented gel keeps its water-holding power through the large bowel. This is the reviewers' interpretation of earlier trials.

A proposed mechanism does not show that the effect happens in people.

None specific.

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Irritable bowel syndrome (IBS)

Low certainty

Fibre helped IBS symptoms a little in pooled trials, mainly soluble fibre (psyllium, ispaghula, calcium polycarbophil). It did not help abdominal pain. A small 1993 trial found most people with IBS preferred calcium polycarbophil to placebo. Insoluble fibre such as bran did not help.

3 studiesPsyllium, ispaghula and calcium polycarbophil (soluble); bran (insolu…

Studies, doses and limits

What the trials found

A 2014 meta-analysis of 14 trials (906 people) found fibre helped overall (RR 0.86, NNT 10); soluble fibre did (RR 0.83, NNT 7) and bran did not (RR 0.90). A 2004 review of 17 trials found fibre helped global symptoms (RR 1.33) and IBS with constipation (RR 1.56), but not abdominal pain; soluble fibre RR 1.55 and insoluble fibre RR 0.89. The authors called the benefit marginal. A 1993 crossover trial in 23 people compared calcium polycarbophil with placebo for six months; 15 of 21 who stated a preference (71%) chose polycarbophil.

Results

A modest, uneven benefit for soluble fibre, especially in IBS with constipation. Insoluble fibre did not help.

Effect sizes as reported

Soluble fibre RR 0.83 (NNT 7) in 2014; RR 1.55 for symptom improvement in the 2004 review (different effect directions because the papers define 'RR' differently).

Why this rating

Low. Small trials of varying quality; the reviews lump psyllium and polycarbophil together; results are marginal.

Form and dose studied

Psyllium, ispaghula and calcium polycarbophil (soluble); bran (insoluble).

Who was studied

Adults with IBS.

Limits

Mixed sizes of benefit; old trials; the 1993 result is a preference vote in 23 people.

Why researchers looked

IBS often involves constipation and bloating, so fibre is tried often.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Not established

Not established in the sources read.

A proposed mechanism does not show that the effect happens in people.

Bloating can occur with fibre; see Safety.

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Inulin: gut bacteria and bowel function in healthy people

Low certainty

Inulin from chicory raised Bifidobacterium (a gut bacterium) in a pooled analysis of 50 studies and helped bowel function in healthy people. A 2016 expert review says inulin does not act as a laxative, and evidence for constipation relief was not found in the sources read. More Bifidobacterium is a bacteria count, not a symptom result.

2 studiesChicory-derived inulin-type fructans (3 to 20 g a day in the trials; …

Studies, doses and limits

What the trials found

A 2023 systematic review with meta-analysis of randomised trials found chicory inulin-type fructans increased Bifidobacterium (SMD 0.83, 95% CI 0.58 to 1.08; 50 studies, 2,525 people) except in people with gastrointestinal disorders, and helped bowel function in healthy people. The abstract does not give bowel-function numbers. Two reviews led by the same author (McRorie) say fermentable, non-viscous fibres such as inulin have no laxative effect.

Results

Probably raises Bifidobacterium and may help bowel function in healthy people. It is not shown to relieve constipation.

Effect sizes as reported

Bifidobacterium SMD 0.83 (95% CI 0.58 to 1.08).

Why this rating

Low for symptoms: the main result is a bacteria count; bowel function data are only summarised in the abstract.

Form and dose studied

Chicory-derived inulin-type fructans (3 to 20 g a day in the trials; this is a trial range, not advice).

Who was studied

People of all ages; benefit was in healthy people.

Limits

Abstract only; bowel numbers unread; the reviews that say inulin is not a laxative are narrative reviews.

Why researchers looked

Inulin is sold as a prebiotic, so researchers tested what it does to gut bacteria and stool.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Established physiology

Gut bacteria ferment inulin, and Bifidobacterium is one group that grows on it. This is established gut biology; it is separate from showing a health benefit.

A proposed mechanism does not show that the effect happens in people.

Inulin ferments in the gut, so gas and bloating are possible; this was not measured in the abstract read.

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Methylcellulose and psyllium gels and gas from inulin

Very low certainty

A small 2026 trial in 22 healthy volunteers tested whether gels of methylcellulose or psyllium cut gas after inulin. Both were linked to less gas in the colon once they arrived there, and methylcellulose added more water than psyllium. This is a scan study in healthy people, not proof of symptom relief.

1 studiesMethylcellulose gel and psyllium gel (trial design only).

Studies, doses and limits

What the trials found

A 3-way randomised crossover trial in 22 healthy volunteers gave 15 g inulin with 15 g methylcellulose, psyllium or maltodextrin (placebo). Overall gas over six hours did not change, but gas after the gels reached the colon was lower (p = 0.02). Both gels increased bowel water; the methylcellulose effect was larger than psyllium for small-bowel water (p = 0.0005) and colon wateriness (p = 0.01). Breath hydrogen over 24 hours did not differ.

Results

A hint that gel fibres calm inulin gas, in healthy people only.

Effect sizes as reported

Colonic gas 180 to 360 minutes, p = 0.02; no change in 24-hour breath hydrogen (p = 1.0).

Why this rating

Very low. Twenty-two healthy volunteers, one test, scan measures, no symptoms.

Form and dose studied

Methylcellulose gel and psyllium gel (trial design only).

Who was studied

Healthy volunteers.

Limits

Not a trial in IBS or constipation; the abstract suggests but did not test help in IBS.

Why researchers looked

People who limit fermentable foods because of gas may want to know if gel fibres can help.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Preliminary mechanism

The gels may slow fermentation and hold water in the bowel; the trial measured this on MRI but the abstract does not prove the mechanism.

A proposed mechanism does not show that the effect happens in people.

None reported in the abstract.

⁶

Wheat dextrin (in a blend) and functional constipation

Not enough evidence

We found no trial of wheat dextrin on its own. In one 2026 trial of 54 adults, a blend of resistant wheat dextrin, pectin, citrus fibre and oat fibre raised bowel movements versus placebo. The blend cannot be credited to wheat dextrin alone. A 2017 review says wheat dextrin is not a laxative and may be constipating.

2 studiesA blend of resistant wheat dextrin with pectin, citrus and oat fibre;…

Studies, doses and limits

What the trials found

The 28-day, double-blind trial in 54 adults found bowel movements rose against placebo (beta 2.43 +/- 0.23, p < 0.001), stool form improved, and bloating, distension and flatulence fell; abdominal pain did not differ. No adverse events were reported. The product has a brand name, so it may have a maker; funding is not in the abstract. The 2017 review by McRorie and McKeown disagrees in principle about wheat dextrin alone, calling it non-laxative and possibly constipating, which this blend trial cannot settle.

Results

No evidence for wheat dextrin by itself. A blend containing it helped in one small trial.

Effect sizes as reported

Bowel movements beta 2.43 (SE 0.23), p < 0.001 (blend versus placebo).

Why this rating

Insufficient for wheat dextrin alone: one small blend trial and a narrative review that disagrees.

Form and dose studied

A blend of resistant wheat dextrin with pectin, citrus and oat fibre; not wheat dextrin alone.

Who was studied

Adults with functional constipation.

Limits

Single centre, 54 people, blend, funding not stated.

Why researchers looked

Wheat dextrin is a common soluble fibre in powders, so people ask whether it helps constipation.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Not established

Not established; the blend contained several fibres.

A proposed mechanism does not show that the effect happens in people.

No adverse events were reported in that trial.

^{7 16}

Fecal incontinence (leaking loose stool)

Low certainty

In 189 adults with fecal incontinence, psyllium cut episodes of leaking loose stool versus placebo, while carboxymethylcellulose (another gel fibre) made them worse and gum arabic did not clearly help. Only psyllium formed a gel in the stool. Symptoms with fibre were mild.

2 studiesPsyllium, gum arabic and carboxymethylcellulose (16 g a day fibre in …

Studies, doses and limits

What the trials found

In a 2014 single-blind trial, adults took placebo or 16 g a day of gum arabic, psyllium or carboxymethylcellulose for about 32 days. Estimated episodes per week were 5.5 on placebo, 2.5 on psyllium, 4.3 on gum arabic and 6.2 on carboxymethylcellulose. Quality of life did not differ. A companion analysis found symptoms were mild; only a feeling of fullness was higher with psyllium, and people with more bloating or fullness were likelier to cut the dose or drop out.

Results

Psyllium helped; carboxymethylcellulose, a fibre not on this page's main list, got worse results. Methylcellulose itself was not tested here.

Effect sizes as reported

Episodes per week: placebo 5.5; psyllium 2.5; gum arabic 4.3; carboxymethylcellulose 6.2.

Why this rating

Low. One trial of 189 people, single-blind, abstract only.

Form and dose studied

Psyllium, gum arabic and carboxymethylcellulose (16 g a day fibre in the trial; not advice).

Who was studied

Community adults with fecal incontinence of loose or liquid stool.

Limits

Different condition from constipation; carboxymethylcellulose is not methylcellulose.

Why researchers looked

Bulk-forming fibre can firm up loose stool, so it was tested for leaking.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Reviewer interpretation

The authors say the psyllium gel in stool is how it helped; this is their explanation.

A proposed mechanism does not show that the effect happens in people.

Fullness and bloating were the symptoms that led some people to stop.

^{4 3}

Blood sugar (psyllium)

Low certainty

In people with type 2 diabetes, psyllium lowered fasting glucose and HbA1c in pooled trials. The results are lab markers and the main meta-analysis has authors from a psyllium maker. People on diabetes medicines should talk to their doctor first.

3 studiesPsyllium.

Studies, doses and limits

What the trials found

A 2020 meta-analysis of 8 trials (395 people with diabetes) found HbA1c lower by 0.91% and fasting glucose lower by 31.71 mg/dL, with lower LDL and triglycerides. A 2015 meta-analysis of 35 trials found fasting glucose lower by 37.0 mg/dL and HbA1c by 0.97% in type 2 diabetes, but no clear effect in people with normal glucose. The 2015 authors are from Procter & Gamble, which sells a psyllium product.

Results

Psyllium lowers blood sugar markers in type 2 diabetes. Other fibres on this page were not tested for this in the sources read.

Effect sizes as reported

HbA1c -0.91% and fasting glucose -31.71 mg/dL (2020); fasting glucose -37.0 mg/dL and HbA1c -0.97% (2015).

Why this rating

Low. Few trials, big differences between trials, and one meta-analysis is industry-linked.

Form and dose studied

Psyllium.

Who was studied

Adults with type 2 diabetes.

Limits

Lab markers; some trials short; industry-linked pooled analysis.

Why researchers looked

Gel fibre slows how fast sugar enters the blood, so it was tested in diabetes.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Reviewer interpretation

Reviews link the effect to gel thickness in the small bowel; the trials did not test the mechanism.

A proposed mechanism does not show that the effect happens in people.

May add to diabetes medicines; see Safety.

^{26 9 16}

Extra LDL lowering when added to statins (psyllium)

Low certainty

In three trials in people already on statins, adding psyllium lowered LDL more than the statin alone. The authors, who worked for a psyllium maker, said the extra drop was like doubling the statin. It is a small pool of trials.

1 studiesPsyllium plus a statin.

Studies, doses and limits

What the trials found

A 2018 meta-analysis of three randomised trials found a significant extra fall in LDL when psyllium was added to a statin (p = 0.001). The abstract gives no numbers. Authors are from Procter & Gamble Health Care.

Results

Possible extra LDL lowering; evidence is small and industry-linked.

Effect sizes as reported

Significant extra LDL lowering; numbers not in the abstract.

Why this rating

Low. Three trials, industry authors, no numbers in the abstract.

Form and dose studied

Psyllium plus a statin.

Who was studied

Adults taking statins.

Limits

Only three trials.

Why researchers looked

People on statins often want to know whether fibre adds anything.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Not established

Not tested.

A proposed mechanism does not show that the effect happens in people.

Do not change cholesterol medicines without a doctor.

⁵

After pouch surgery for ulcerative colitis (methylcellulose)

Very low certainty

In a small crossover study of 13 people after pouch surgery, methylcellulose (Citrucel) did not change stool frequency, pouch function, bloating, stool form or continence. The authors saw little role for fibre supplements there. This is a very small, specialised group.

1 studiesMethylcellulose (Citrucel) 1 tablespoon twice a day in the trial; not…

Studies, doses and limits

What the trials found

Thirteen people took methylcellulose, pectin or nothing for 2 weeks each in random order. There was no significant effect of either supplement on any outcome.

Results

No benefit found in this group. This is evidence against, but only for 13 people.

Effect sizes as reported

No significant difference on any outcome.

Why this rating

Very low. Thirteen people, one 1997 study.

Form and dose studied

Methylcellulose (Citrucel) 1 tablespoon twice a day in the trial; not advice.

Who was studied

People who had pouch surgery for ulcerative colitis.

Limits

Very small; specialised surgery; not representative of everyday constipation.

Why researchers looked

Fibre supplements are often suggested after this surgery, so the study asked whether they help.

Traditional use

Fibre supplements are sold for regularity and gut comfort. A normal job in the gut is not proof that a pill or powder adds benefit; each item says which fibre was tested.

Proposed mechanism Not established

Not applicable.

A proposed mechanism does not show that the effect happens in people.

None reported.

²³

Connections to the rest of health

How Fibre supplements compared connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Evidence status	Context	Studies
Digestive Support	Moderate certainty	Constipation (fibre supplements, mostly psyllium): In adults with long-term constipation, fibre supplements helped in pooled trials. Psyllium has the most evidence and was graded moderate in an over-the-counter review. Gas was more common. The best evidence is for psyllium; it does not carry over automatically to the other fibres. Irritable bowel syndrome (IBS): Fibre helped IBS symptoms a little in pooled trials, mainly soluble fibre (psyllium, ispaghula, calcium polycarbophil). It did not help abdominal pain. A small 1993 trial found most people with IBS preferred calcium polycarbophil to placebo. Insoluble fibre such as bran did not help.	^{33 20 13 17 2 24}
Digestive Support	Low certainty	Methylcellulose and calcium polycarbophil for constipation: Methylcellulose and calcium polycarbophil are sold as bulk-forming laxatives, but the trials we could read are old and small. A 1988 study found methylcellulose raised stool frequency and stool water. A review in older adults found calcium polycarbophil better than placebo in the short term. We found no trial that compared them head to head with psyllium.	^{10 13}
Cholesterol Balance	Moderate certainty	Cholesterol (psyllium): Psyllium taken regularly lowered LDL ('bad') cholesterol modestly in pooled trials. This is a lab marker, not proof of fewer heart attacks. The evidence is for psyllium; the sources read say non-gel fibres such as inulin and wheat dextrin do not share this effect.	^{12 27 16}
Digestive Support	Low certainty	Why the five fibres behave differently: Two reviews with the same lead author say two traits explain most differences: how thick a gel the fibre makes, and whether gut bacteria ferment it. By their account, psyllium is a thick, unfermented gel and helps constipation and cholesterol, while inulin and wheat dextrin are readily fermented, non-viscous fibres that do not act as laxatives.	^{15 16 4}
Digestive Support	Low certainty	Inulin: gut bacteria and bowel function in healthy people: Inulin from chicory raised Bifidobacterium (a gut bacterium) in a pooled analysis of 50 studies and helped bowel function in healthy people. A 2016 expert review says inulin does not act as a laxative, and evidence for constipation relief was not found in the sources read. More Bifidobacterium is a bacteria count, not a symptom result.	^{18 15}
Digestive Support	Very low certainty	Methylcellulose and psyllium gels and gas from inulin: A small 2026 trial in 22 healthy volunteers tested whether gels of methylcellulose or psyllium cut gas after inulin. Both were linked to less gas in the colon once they arrived there, and methylcellulose added more water than psyllium. This is a scan study in healthy people, not proof of symptom relief. Wheat dextrin (in a blend) and functional constipation: We found no trial of wheat dextrin on its own. In one 2026 trial of 54 adults, a blend of resistant wheat dextrin, pectin, citrus fibre and oat fibre raised bowel movements versus placebo. The blend cannot be credited to wheat dextrin alone. A 2017 review says wheat dextrin is not a laxative and may be constipating.	^{6 7 16 4 3 23}
Blood Sugar Balance	Low certainty	Blood sugar (psyllium): In people with type 2 diabetes, psyllium lowered fasting glucose and HbA1c in pooled trials. The results are lab markers and the main meta-analysis has authors from a psyllium maker. People on diabetes medicines should talk to their doctor first.	^{26 9 16}
Cholesterol Balance	Low certainty	Extra LDL lowering when added to statins (psyllium): In three trials in people already on statins, adding psyllium lowered LDL more than the statin alone. The authors, who worked for a psyllium maker, said the extra drop was like doubling the statin. It is a small pool of trials.	⁵

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Gut Health	Biological association	Moderate certainty	Studied for: Constipation (fibre supplements, mostly psyllium) Studied for: Methylcellulose and calcium polycarbophil for constipation	^{33 20 13 10 15 16 4 17 2 24 18 6 7 3}
Digestive System	Biological association	Moderate certainty	Studied for: Constipation (fibre supplements, mostly psyllium) Studied for: Methylcellulose and calcium polycarbophil for constipation	^{33 20 13 10 12 27 16 15 4 17 2 24 18 7 3 26 9 23}
Heart Circulation	Biological association	Moderate certainty	Studied for: Cholesterol (psyllium) Studied for: Extra LDL lowering when added to statins (psyllium)	^{12 27 16 5}

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Esophageal obstruction (gullet blockage)	Adverse effect or risk	Documented risk	A US federal rule warns of choking and gullet blockage with these fibres taken without enough fluid. Preparation or compound: Psyllium, methylcellulose, polycarbophil taken dry	^{28 22}
Psyllium allergy	Adverse effect or risk	Case reports	Allergic sensitisation from inhaled dust and anaphylaxis after swallowing have been reported. Preparation or compound: Psyllium powder	^{14 1}
Chronic constipation		Clinical trial evidence	Fibre supplements, mostly psyllium, helped in pooled trials. Preparation or compound: Psyllium	^{33 20}
Esophageal obstruction	Adverse effect or risk	Documented risk	A US federal rule warns of choking and blockage with swelling fibres taken without enough fluid. Preparation or compound: Dry swelling fibres	^{28 22}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
LDL cholesterol	Demonstrated clinical effect	Moderate certainty	Lowered modestly by psyllium in meta-analyses. Preparation or compound: Psyllium	^{12 27}
Response to treatment in chronic constipation	Biological association	Moderate certainty	Measured in trials: higher with fibre. A lab change is not the same as a health benefit.	³³
LDL cholesterol	Biological association	Moderate certainty	Measured in trials: lower. A lab change is not the same as a health benefit.	^{12 27}
Fasting glucose and HbA1c	Biological association	Low certainty	Measured in trials: lower. A lab change is not the same as a health benefit.	^{26 9}
Bifidobacterium abundance	Biological association	Low certainty	Measured in trials: higher. A lab change is not the same as a health benefit.	¹⁸
Episodes of fecal incontinence per week	Biological association	Low certainty	Measured in trials: lower with psyllium. A lab change is not the same as a health benefit.	⁴

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
Bifidobacterium	Preliminary mechanism	Human	Inulin-type fructans raised its abundance in a pooled analysis.	¹⁸
Soluble and insoluble fibre	Preliminary mechanism	Expert review	Reviews sort the five fibres by gel thickness and fermentability.	^{15 16}

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Psyllium (ispaghula husk)	Biological association	Human	Largest body of trial evidence on this page: constipation, cholesterol, blood sugar markers and fecal incontinence.	^{33 12 4}
Methylcellulose	Biological association	Human	Called a non-fermentable gelling agent; raised stool water in a 1988 trial; made more bowel water than psyllium on scans in 22 healthy people.	^{10 6}
Calcium polycarbophil	Biological association	Human	Listed with psyllium and methylcellulose in the US labelling rule. Better than placebo in short-term constipation in a review of older adults; preferred to placebo by 15 of 21 people with IBS in a 1993 trial.	^{28 13 24}
Inulin (chicory)	Biological association	Human	Raises Bifidobacterium in pooled trials; reviews say it does not act as a laxative.	^{18 15}
Wheat dextrin	Biological association	Human	No trial of wheat dextrin alone was found; one blend trial helped constipation.	^{7 16}

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).

Evidence at a glance: what the research found for 12 outcomes

2Moderate certainty

7Low certainty

2Very low certainty

1Not enough evidence

Each outcome below is one thing researchers measured. Certainty is how far the evidence can be trusted, not how well it works. The full studies are on the next tab.

Constipation (fibre supplements, mostly psyllium) 3 studies Moderate certainty Methylcellulose and calcium polycarbophil for constipation 2 studies Low certainty Cholesterol (psyllium) 3 studies Moderate certainty Why the five fibres behave differently 3 studies · 189 people in trials Low certainty Irritable bowel syndrome (IBS) 3 studies Low certainty Inulin: gut bacteria and bowel function in healthy people 2 studies Low certainty Methylcellulose and psyllium gels and gas from inulin 1 study Very low certainty Wheat dextrin (in a blend) and functional constipation 2 studies Not enough evidence Fecal incontinence (leaking loose stool) 2 studies · 189 people in trials Low certainty Blood sugar (psyllium) 3 studies Low certainty Extra LDL lowering when added to statins (psyllium) 1 study Low certainty After pouch surgery for ulcerative colitis (methylcellulose) 1 study Very low certainty

The evidence

The research centre for Fibre supplements compared. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing fibre summary and the earlier psyllium page, then read the US labelling rule and MedlinePlus and re-read PubMed abstracts for reviews, meta-analyses and trials. Only abstracts were read for studies. The NHS and NCCIH pages could not be opened and are marked unread.

Study library: every study we checked 33

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Bardy 1987 Occupational asthma and IgE sensitization in a pharmaceutical company processing psyllium. Am Rev Respir Dis · PMID 3579003 · DOI	Cross sectional	140 Workers at a pharmaceutical plant processing psyllium	Occupational exposure to psyllium dust seed husk Occupational Processing about 5 times a year, under 10 days each	19% (23/120) had a positive skin test to psyllium and 26% (31/118) had raised specific IgE; 32% had at least one of the two. Five of 18 tested workers had an immediate bronchoconstriction reaction on challenge. Sensitization 32% of tested workers Methods, limits and funding Outcomes: Occupational asthma, skin test, IgE antibodies Limitations: Abstract truncated; cross-sectional. Read: abstract
Bijkerk 2004 Systematic review: the role of different types of fibre in the treatment of irritable bowel syndrome. Aliment Pharmacol Ther · PMID 14984370 · DOI	Systematic review	People with irritable bowel syndrome; 17 randomised trials up to 2002	Soluble fibre (psyllium, ispaghula, calcium polycarbophil) and insoluble fibre (corn, wheat bran) Mixed · vs Placebo	Fibre in general helped global symptoms (RR 1.33) and IBS with constipation (RR 1.56), but not abdominal pain. Soluble fibre (psyllium, ispaghula, calcium polycarbophil) helped (RR 1.55); insoluble fibre did not (RR 0.89). The authors call the benefit marginal. All fibre RR 1.33; soluble RR 1.55; insoluble RR 0.89 (All fibre 1.19 to 1.50; soluble 1.35 to 1.78; insoluble 0.72 to 1.11) Methods, limits and funding Outcomes: Global IBS symptom relief; abdominal pain Limitations: Trials up to 2002; none in primary care. The soluble-fibre group lumps psyllium, ispaghula and polycarbophil together, so it does not separate them. Funding and conflicts: Not stated in the abstract. Read: abstract
Bliss 2011 Symptoms associated with dietary fiber supplementation over time in individuals with fecal incontinence. Nurs Res · PMID 21543963 · DOI	Randomised controlled trial	189 189 adults with fecal incontinence	Gum arabic, psyllium or carboxymethylcellulose Dry fibre supplements 16 g of fibre a day (studied in the trial) About 38 days · vs Placebo	Symptoms were mild in all groups. Only a feeling of fullness in the psyllium group differed from placebo. Flatus, belching, fullness and bloating were somewhat higher on the full fibre amount than at baseline in all groups. People with more bloating or fullness were more likely to drop out or cut the amount. Fullness higher with psyllium than placebo; other symptoms not different (Not reported in the abstract) Methods, limits and funding Outcomes: Severity of gut symptoms; dropout Limitations: People with fecal incontinence, not constipation; the abstract does not give numbers. Funding and conflicts: Not stated in the abstract. Read: abstract
Bliss 2014 Dietary fiber supplementation for fecal incontinence: a randomized clinical trial. Res Nurs Health · PMID 25155992 · DOI	Controlled trial	189 Community adults with fecal incontinence of loose or liquid stool	Psyllium vs gum arabic vs carboxymethylcellulose vs placebo seed husk 16 g total fibre/day 32 days (after 14-day baseline) · vs Placebo	Psyllium cut episodes versus placebo; carboxymethylcellulose increased them. Only psyllium formed a gel in stool. Intolerance was low. Quality of life did not differ. Estimated episodes per week: placebo 5.5, psyllium 2.5, gum arabic 4.3, carboxymethylcellulose 6.2 Methods, limits and funding Outcomes: Fecal incontinence episodes per week Limitations: Single-blind; short; quality of life no different. Funding and conflicts: Not stated in abstract Read: abstract
Brum 2018 Meta-Analysis of Usefulness of Psyllium Fiber as Adjuvant Antilipid Therapy to Enhance Cholesterol Lowering Efficacy of Statins. Am J Cardiol · PMID 30078477 · DOI	Meta-analysis	People already taking statins; 3 RCTs	psyllium (Plantago ovata) seed husk plus statin seed husk Not given in abstract 4 to 12 weeks · vs Statin alone	Adding psyllium lowered LDL more than the statin alone; the authors say the reduction was equal to doubling the statin dose. Significant extra LDL lowering (p = 0.001); numbers not in abstract Methods, limits and funding Outcomes: LDL cholesterol Limitations: Only 3 trials, short; numeric effects not in the abstract. Funding and conflicts: Industry-linked: authors from Procter & Gamble Health Care (maker of a psyllium brand). Read: abstract
Dellschaft 2026 Clinical Trial: Randomised Placebo-Controlled Trial of Methylcellulose and Psyllium Gels on Inulin-Induced Colonic Gas. Aliment Pharmacol Ther · PMID 42728685 · DOI	Randomised controlled trial	22 22 healthy volunteers (3-way crossover)	Methylcellulose gel or psyllium gel, each with inulin Methylcellulose (non-fermentable gelling agent) and psyllium 15 g of each fibre given with 15 g inulin (studied in the trial) Single test sessions, MRI scans hourly for 6 hours and breath tests for 24 hours · vs Maltodextrin placebo with inulin	Both gels were linked to less colonic gas after they reached the colon (p = 0.02). Both increased small-bowel free water and made colon contents more watery; methylcellulose did more than psyllium. Breath hydrogen over 24 hours did not differ between groups. Gas (MRI, 180 to 360 min) p = 0.02; small-bowel water methylcellulose more than psyllium p = 0.0005; colon wateriness greater after methylcellulose than psyllium p = 0.01 (Not reported in the abstract) Methods, limits and funding Outcomes: Colonic gas on MRI; bowel water; breath hydrogen Limitations: Only 22 healthy people, one dose, measuring gas and water on scans. It is not a trial of constipation relief or of symptoms. Funding and conflicts: Funding is not stated in the abstract. Registered as NCT06291272. Registration: NCT06291272 Read: abstract
Di Minno 2026 Combination of Dietary Fibers From Different Food Origins as a Treatment for Adults With Functional Constipation: A Randomized Clinical Trial. Food Sci Nutr · PMID 42369644 · DOI	Randomised controlled trial	54 54 adults with functional constipation	A blended product (resistant wheat dextrin with pectin, citrus fibre and oat fibre) Sachets Two sachets a day (studied in the trial) 28 days · vs Placebo	The blend increased bowel movements and improved stool form against placebo, and eased bloating, distension and flatulence. Abdominal pain did not differ. No adverse events were reported. Bowel movements beta 2.43 (SE 0.23), p < 0.001 (Not reported in the abstract) Methods, limits and funding Outcomes: Bowel movements; stool form; bloating, distension, flatulence Limitations: A mixed product, so the result cannot be credited to wheat dextrin alone. Small, one centre. Funding is not stated in the abstract and the product has a name (MNS-36), so a maker link is possible. Funding and conflicts: Not stated in the abstract. Read: abstract
Drugs and Lactation Database (NICHD) 2021 Psyllium (LactMed entry) Drugs and Lactation Database (LactMed) · PMID 30000405	Authoritative guidance	Breastfeeding	Psyllium seed husk	LactMed (2021 update): few data on psyllium in breastfeeding, but it is not absorbed from the gut so it cannot enter breast milk; acceptable to use during breastfeeding. Methods, limits and funding Outcomes: Lactation safety Limitations: Short entry; relies on two references. Funding and conflicts: Public database (NICHD) Read: abstract
Gibb 2015 Psyllium fiber improves glycemic control proportional to loss of glycemic control: a meta-analysis of data in euglycemic subjects, patients at risk of type 2 diabetes mellitus, and patients being treated for type 2 diabetes mellitus. Am J Clin Nutr · PMID 26561625 · DOI	Meta-analysis	35 RCTs in people without diabetes, at risk of type 2 diabetes, and with type 2 diabetes	psyllium (Plantago ovata) seed husk seed husk Dosed before meals in multi-week studies Multi-week · vs Control	In type 2 diabetes, fasting glucose fell and HbA1c fell. No significant glucose lowering in people with normal glucose; modest improvement in pre-diabetes. Fasting glucose -37.0 mg/dL (P < 0.001); HbA1c -0.97% (P = 0.048) Methods, limits and funding Outcomes: Fasting glucose, HbA1c Limitations: Some clinical records came from the company's files, not only published papers. Funding and conflicts: Industry-linked: authors from Procter & Gamble, which makes a psyllium product, and the search used the company's own records. Read: abstract
Hamilton 1988 Clinical evaluation of methylcellulose as a bulk laxative. Dig Dis Sci · PMID 2839321 · DOI	Clinical trial	109 50 healthy people and 59 people with long-term constipation	Methylcellulose (compared in one part of the study with psyllium) Methylcellulose Daily amounts of 1, 2 or 4 g methylcellulose, or 3.4 g psyllium (studied in the trial) · vs Psyllium 3.4 g a day in the constipation part	In healthy people, 4 g a day increased stool frequency, stool water and stool solids. In the constipated group, all methylcellulose amounts and the psyllium amount increased stool frequency, water and solids. The authors call even 1 g a day an effective laxative. Single-stool weight did not rise. Statistically significant increases; numbers not in the abstract (Not reported in the abstract) Methods, limits and funding Outcomes: Stool frequency, stool water, stool solids Limitations: A 1988 study; the abstract does not say it had a placebo arm in the constipated group, and does not give numbers. It does not show methylcellulose beats or equals psyllium. Funding and conflicts: Not stated in the abstract. Read: abstract
Hefny 2018 Intestinal obstruction caused by a laxative drug (Psyllium): A case report and review of the literature. Int J Surg Case Rep · PMID 30321826 · DOI	Case report	1 21-year-old man with constipation	Psyllium husk (granules) seed husk Two days after discharge	Developed incomplete intestinal obstruction after taking psyllium husks without enough fluid; treated without surgery. Authors say similar cases include esophageal obstruction in older people and after gastric banding, and that psyllium given with oral contrast may precipitate obstruction where one already exists. Incomplete obstruction Methods, limits and funding Outcomes: Intestinal obstruction Limitations: One case plus literature review. Read: abstract
Jovanovski 2018 Effect of psyllium (Plantago ovata) fiber on LDL cholesterol and alternative lipid targets, non-HDL cholesterol and apolipoprotein B: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr · PMID 30239559 · DOI	Meta-analysis	1924 Adults with or without high cholesterol; 28 RCTs of 3 weeks or longer	psyllium (Plantago ovata) seed husk seed husk Median about 10.2 g/day 3 weeks or longer · vs Control	Lower LDL, non-HDL and apoB. GRADE: moderate quality for LDL and non-HDL (downgraded for inconsistency), high for apoB. LDL MD -0.33 mmol/L; non-HDL -0.39 mmol/L; apoB -0.05 g/L (LDL -0.38 to -0.27; non-HDL -0.50 to -0.27; apoB -0.08 to -0.03) Methods, limits and funding Outcomes: LDL cholesterol, non-HDL cholesterol, apolipoprotein B Limitations: Inconsistency between trials; effect on heart events not measured. Funding and conflicts: Not stated in abstract; read abstract only. Authors are from a university nutrition centre; funding not read. Registration: NCT03346733 Read: abstract
Kang 2021 Medical Management of Constipation in Elderly Patients: Systematic Review. J Neurogastroenterol Motil · PMID 34642269 · DOI	Systematic review	People over 65 with constipation; 23 randomised trials of laxatives	Laxatives including psyllium and calcium polycarbophil Mixed Short term; the authors say up to 3 months · vs Placebo or other laxatives	Psyllium, calcium polycarbophil, lactulose, lactitol, polyethylene glycol, magnesium hydroxide and others were more effective than placebo in the short term. Side effects were generally similar between arms. Quality of the trials was not high and most were small. No pooled numbers in the abstract (Not reported in the abstract) Methods, limits and funding Outcomes: Stool and constipation outcomes; side effects Limitations: Small, lower-quality trials in older adults; calcium polycarbophil is one of many agents and is not singled out. Funding and conflicts: Not stated in the abstract. Read: abstract
Khalili 2003 Psyllium-associated anaphylaxis and death: a case report and review of the literature. Ann Allergy Asthma Immunol · PMID 14700444 · DOI	Case report	1 42-year-old woman; plus literature review	Psyllium-based product seed husk	Fatal anaphylaxis after eating a psyllium-based product. The review found psyllium allergy well described in health care and pharmaceutical workers, from airway symptoms on inhaling to anaphylaxis on swallowing, with a clear link to atopy. Methods, limits and funding Outcomes: Fatal anaphylaxis; review of psyllium allergy Limitations: One death; the review covered MEDLINE to 2002. Read: abstract
McRorie 2016 Fermented Fiber Supplements Are No Better Than Placebo for a Laxative Effect. Dig Dis Sci · PMID 27680987 · DOI	Narrative review	Review of well-controlled clinical studies of fibre and stool	Soluble and insoluble fibres, including psyllium, inulin and wheat dextrin Mixed	The authors conclude that a fibre needs to resist fermentation and hold water through the large bowel to act as a laxative. They say psyllium (not fermented, forms a gel) does this, while readily fermented fibres, whether gel-forming or not, do not change stool output or water. They list inulin and wheat dextrin as soluble fibres with no effect on viscosity. No numbers in the abstract (Not applicable) Methods, limits and funding Outcomes: Stool water, stool output, laxative effect Limitations: A narrative review by authors who interpret the evidence; not a systematic search with pooled results. Read from the abstract only. Funding and conflicts: Not stated in the abstract; not checked. Read: abstract
McRorie 2017 Understanding the Physics of Functional Fibers in the Gastrointestinal Tract: An Evidence-Based Approach to Resolving Enduring Misconceptions about Insoluble and Soluble Fiber. J Acad Nutr Diet · PMID 27863994 · DOI	Narrative review	Review of isolated fibre supplements and three health effects	Gel-forming fibres (beta-glucan, psyllium, raw guar) versus non-viscous soluble fibres (inulin, fructo-oligosaccharides, wheat dextrin) and wheat bran Mixed	The authors say cholesterol lowering and better blood sugar control track with how thick (viscous) the fibre gel is, so gel-formers such as psyllium show them and non-viscous fibres such as inulin and wheat dextrin do not. For a laxative effect the fibre must resist fermentation and stay intact in the large bowel. They say soluble fermentable fibres do not act as laxatives and some fibres, including wheat dextrin, can be constipating. No numbers in the abstract (Not applicable) Methods, limits and funding Outcomes: Cholesterol, blood sugar control and stool form Limitations: A narrative review; its claim that wheat dextrin can be constipating is the authors' statement and was not checked against trials here. Read from the abstract only. Funding and conflicts: Not stated in the abstract; not checked. Read: abstract
Moayyedi 2014 The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis. Am J Gastroenterol · PMID 25070054 · DOI	Meta-analysis	906 Adults with irritable bowel syndrome; 14 RCTs	Fibre supplements (soluble fibre and bran compared) unspecified Varied Varied · vs Placebo, control or usual care	Fibre helped overall. The benefit was seen only with soluble fibre, not bran. No evidence of harm from bran was found. All fibre RR 0.86, NNT 10; soluble fibre RR 0.83, NNT 7; bran RR 0.90 (not significant) (All 0.80 to 0.94; soluble 0.73 to 0.94; bran 0.79 to 1.03) Methods, limits and funding Outcomes: Staying symptomatic after treatment Limitations: Soluble fibre trials not all psyllium (abstract does not say how many used psyllium); symptom outcomes self-reported. Funding and conflicts: Not stated in abstract Read: abstract
Nagy 2023 Effect of chicory-derived inulin-type fructans on abundance of Bifidobacterium and on bowel function: a systematic review with meta-analyses. Crit Rev Food Sci Nutr · PMID 35833477 · DOI	Meta-analysis	2525 People of all ages (0 to 83 years); 50 randomised studies on Bifidobacterium, others on bowel function	Chicory-derived inulin-type fructans Foods or supplements 3 to 20 g a day (studied in trials) At least 7 days · vs Placebo or control	Inulin-type fructans raised Bifidobacterium abundance. Helpful effects on bowel function were significant in healthy people. Bifidobacterium SMD 0.83 (95% CI 0.58 to 1.08; p < 0.01; 50 studies, 2,525 people) Methods, limits and funding Outcomes: Bifidobacterium abundance; bowel function Limitations: Bifidobacterium count is a gut-bacteria marker, not a symptom. The abstract says no significant bifidogenic effect in gastrointestinal disorders. Bowel-function numbers were not in the abstract. Funding and conflicts: Not stated in the abstract. Registered as PROSPERO CRD42020162892. Registration: PROSPERO CRD42020162892 Read: abstract
Nordström 1987 Influence of wheat bran and of a bulk-forming ispaghula cathartic on the bioavailability of digoxin in geriatric in-patients. Drug Nutr Interact · PMID 3038494	Controlled trial	30 Geriatric hospital in-patients taking digoxin	Ispaghula bulk cathartic (Vi-Siblin S) vs wheat bran seed husk 4 weeks · vs Wheat bran + digoxin	Wheat bran lowered digoxin levels at 2 weeks but not at 4. Ispaghula had no influence at any time; authors concluded no clinically relevant effect on digoxin in these patients. No change with ispaghula (14 patients) Methods, limits and funding Outcomes: Blood digoxin levels Limitations: Small, 1987, one formulation, no true placebo arm. Read: abstract
Rao 2021 Efficacy and Safety of Over-the-Counter Therapies for Chronic Constipation: An Updated Systematic Review. Am J Gastroenterol · PMID 33767108 · DOI	Systematic review	Adults with chronic constipation; 41 RCTs of 4 weeks or longer, over-the-counter products	Over-the-counter laxatives including psyllium unspecified Varied 4 weeks or longer · vs Placebo or comparator	Psyllium had moderate evidence (grade B). Polyethylene glycol and senna had good evidence (grade A). Diarrhea, nausea, bloating and abdominal pain were common adverse events; no serious adverse events were reported. Grade B recommendation for psyllium Methods, limits and funding Outcomes: Strength of evidence per product class Limitations: Variable study design, outcome measures, duration and small samples. Funding and conflicts: Funded by Bayer US LLC; authors report consulting for Bayer and other industry ties. Read: abstract
Salguero Molpeceres 2003 [Esophageal obstruction caused by dietary fiber from Plantago ovata, a complication preventable by adequate information]. Gastroenterol Hepatol · PMID 12681118	Case report	1 41-year-old woman	Plantago ovata granules seed husk One tablespoonful of granules Single episode	Chest pain and regurgitation after swallowing granules held in the mouth then taken with 250 ml of water; a mass blocked the lower esophagus; a mild hiatus hernia was found. The authors reviewed other cases: all used granules, most with too little liquid, some with earlier esophageal disease; powder probably carries lower risk (authors' view). Esophageal obstruction Methods, limits and funding Outcomes: Esophageal obstruction Limitations: Spanish-language case report; one case. Read: abstract
Shin 2022 Acute esophageal obstruction after ingestion of psyllium seed husk powder: A case report. World J Clin Cases · PMID 35321163 · DOI	Case report	1 76-year-old man with Parkinson's disease	Psyllium seed husk powder seed husk Single episode	Severe swallowing difficulty about 10 hours after ingestion; CT showed a 2.0 x 2.5 cm mass near the stomach junction; removed with an endoscopic net after grinding. Esophageal bezoar Methods, limits and funding Outcomes: Esophageal obstruction Limitations: One case; Parkinson's disease may slow swallowing. Funding and conflicts: None declared Read: abstract
Thirlby 1997 Pectin and methyl cellulose do not affect intestinal function in patients after ileal pouch-anal anastomosis. Am J Gastroenterol · PMID 8995946	Randomised controlled trial	13 13 people who had pouch surgery for ulcerative colitis	Citrucel (methylcellulose) or pectin Methylcellulose One tablespoon twice daily (studied in the trial) Three 2-week periods with washouts, crossover · vs No supplement	No significant effect of either supplement on stool frequency, pouch function, bloating, stool consistency or continence. The authors saw little role for fibre supplements in these patients. No significant difference (Not reported in the abstract) Methods, limits and funding Outcomes: Stool frequency, pouch function, bloating, stool consistency, continence Limitations: Only 13 people after a specific surgery; a small crossover study. It says nothing about everyday constipation. Funding and conflicts: Not stated in the abstract. Read: abstract
Toskes 1993 Calcium polycarbophil compared with placebo in irritable bowel syndrome. Aliment Pharmacol Ther · PMID 8439642 · DOI	Randomised controlled trial	23 23 people with irritable bowel syndrome	Calcium polycarbophil tablets Calcium polycarbophil 6 g a day, twelve 0.5 g tablets (studied in the trial) 6 months, crossover · vs Matching placebo tablets	Of 21 people who stated a preference, 15 (71%) chose polycarbophil for symptom relief. Ease of passing stool and bloating were rated better than placebo. 15 of 21 preferred polycarbophil (71%) (Not reported in the abstract) Methods, limits and funding Outcomes: Preference for treatment; symptom diary scores Limitations: A 1993 study of 23 people; a preference result, and the abstract gives no p-value for it. Too small to be conclusive. Funding and conflicts: Not stated in the abstract. Read: abstract
Wiesner 2021 Levothyroxine Interactions with Food and Dietary Supplements-A Systematic Review. Pharmaceuticals (Basel) · PMID 33801406 · DOI	Systematic review	Levothyroxine users; 63 studies on food and supplements	Fibre (among many foods) unspecified	Limited evidence that fibre decreased levothyroxine absorption. Keeping a time gap between levothyroxine and food or supplements was suggested as an effective way to avoid such interactions. Methods, limits and funding Outcomes: Levothyroxine absorption Limitations: Fibre evidence limited and not specific to psyllium. Funding and conflicts: No conflict of interest declared Read: abstract
Xiao 2020 The effect of psyllium consumption on weight, body mass index, lipid profile, and glucose metabolism in diabetic patients: A systematic review and dose-response meta-analysis of randomized controlled trials. Phytother Res · PMID 31919936 · DOI	Meta-analysis	395 Adults with diabetes; 8 RCTs (9 arms)	psyllium (Plantago ovata) seed husk seed husk Dose-response analysed; amounts not in abstract Varied · vs Control	Lower triglycerides, LDL, fasting glucose and HbA1c. No change in HDL, BMI, total cholesterol or weight. HbA1c -0.91%; fasting glucose -31.71 mg/dL; LDL -8.96 mg/dL; triglycerides -19.18 mg/dL (HbA1c -1.31 to -0.51; glucose -50.04 to -13.38; LDL -13.39 to -4.52; TG -31.76 to -6.60) Methods, limits and funding Outcomes: Triglycerides, LDL, fasting glucose, HbA1c, weight, BMI Limitations: Very high heterogeneity (I2 97 to 99%); small trials. (Abstract prints one glucose unit as ml/dl; read as mg/dL.) Funding and conflicts: Not stated in abstract Read: abstract
Zhu 2024 Plantago consumption significantly reduces total cholesterol and low-density lipoprotein cholesterol in adults: A systematic review and meta-analysis. Nutr Res · PMID 38688104 · DOI	Meta-analysis	2769 Adults; 29 RCTs	Plantago products (husk or psyllium, soluble fibre subgroups) seed husk or seed Varied Varied · vs Control	Total cholesterol and LDL fell; no substantial effect on HDL or triglycerides overall. Authors estimated about a 7% lower cardiovascular event risk (a modelled estimate, not a trial result). Total cholesterol -0.28 mmol/L; LDL -0.35 mmol/L Methods, limits and funding Outcomes: Total cholesterol, LDL, HDL, triglycerides Limitations: Abstract gives no confidence intervals or heterogeneity; modelled risk figure is an estimate. Funding and conflicts: Not stated in abstract Read: abstract
s-cfr-201-319 US Code of Federal Regulations, Title 21, section 201.319: required warnings and directions for water-soluble gums, hydrophilic gums and hydrophilic mucilloids (including calcium polycarbophil, methylcellulose and psyllium); last amendment shown 2007-03-29 · Source	Regulation n/a			Methods, limits and funding Read: full-text
s-ema-ispaghula-husk EMA/HMPC Community herbal monograph on Plantago ovata Forssk., seminis tegumentum (ispaghula husk), Revision 1 · Source	Authoritative guidance n/a			Methods, limits and funding Read: summary-only
s-medlineplus-psyllium MedlinePlus Drug Information: Psyllium (AHFS patient information) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-nccih-psyllium NCCIH: psyllium page · Source	Authoritative guidance n/a			Methods, limits and funding Read: not-found
s-nhs-ispaghula NHS: ispaghula husk medicine pages · Source	Reference database n/a			Methods, limits and funding Read: not-found
van der Schoot 2022 The Effect of Fiber Supplementation on Chronic Constipation in Adults: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials. Am J Clin Nutr · PMID 35816465 · DOI	Meta-analysis	1251 Adults with chronic constipation; 16 RCTs	Fibre supplements (psyllium and pectin had significant effects) unspecified Subgroups by dose; benefit only above 10 g/day Benefit clearer at 4 weeks or more · vs Placebo or control	66% (311/473) responded to fibre vs 41% (134/329) to control. Stool frequency up. Stool consistency improved. Flatulence higher with fibre. Responders RR 1.48; stool frequency SMD 0.72; consistency SMD 0.32; flatulence SMD 0.80 (RR 1.17 to 1.88; frequency 0.36 to 1.08; consistency 0.18 to 0.46; flatulence 0.47 to 1.13) Methods, limits and funding Outcomes: Response to treatment, stool frequency, stool consistency, flatulence Limitations: Considerable heterogeneity (I2 86% for stool frequency); all fibre types pooled; psyllium subgroup numbers not in abstract. Funding and conflicts: No conflict statement read in abstract Registration: PROSPERO CRD42020191404 Read: abstract

What we do not know yet

No trial compared all five fibres for symptoms.
Methylcellulose and calcium polycarbophil have only old, small trials in the abstracts read.
No trial of wheat dextrin alone was found.
Amounts of fibre in foods were not read from USDA or NIH pages.
NHS and NCCIH pages could not be opened.
Pregnancy and children's safety data were not found for these fibres.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue before the page changes.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Metabolic 1

●

LDL cholesterol

Lower in trials

The cholesterol carried in LDL particles, often called 'bad' cholesterol.

Moderate certainty

Results and what it means

Why it was measured

To see whether psyllium changes a blood marker linked with heart disease risk.

Statistical vs. clinical meaning

A lab-marker fall, not proof of fewer heart attacks.

Safety implication

People taking cholesterol medicines should not change them without a doctor.

Study	Result	People	Product
¹²	LDL lower by 0.33 mmol/L; non-HDL lower by 0.39 mmol/L	28 trials, 1,924 adults	Psyllium
²⁷	LDL lower by 0.35 mmol/L; total cholesterol lower by 0.28 mmol/L	29 trials, 2,769 adults	Plantago (psyllium) products

^{12 27}

Other 4

●

Response to treatment in chronic constipation

Higher with fibre in trials

The share of people whose constipation improved enough to count as a response in a trial.

Moderate certainty

Results and what it means

Why it was measured

To see whether fibre supplements help more people than a control does.

Statistical vs. clinical meaning

A clear benefit across trials, but the trials differed a lot and the fibres were mixed.

Safety implication

Flatulence was higher with fibre (SMD 0.80).

Study	Result	People	Product
³³	66% (311 of 473) responded to fibre versus 41% (134 of 329) on control; RR 1.48	16 trials, 1,251 adults with chronic constipation	Fibre supplements, several types, mostly psyllium

³³

●

Fasting glucose and HbA1c

Lower in trials

Fasting glucose is the blood sugar level after not eating. HbA1c reflects average blood sugar over about 3 months.

Low certainty

Results and what it means

Why it was measured

To see whether psyllium changes blood sugar control in type 2 diabetes.

Statistical vs. clinical meaning

A lab-marker improvement from trials with big differences; one analysis is industry-linked.

Safety implication

People on glucose-lowering medicines should ask their doctor.

Study	Result	People	Product
²⁶	HbA1c -0.91%; fasting glucose -31.71 mg/dL	8 trials, 395 adults with diabetes	Psyllium
⁹	Fasting glucose -37.0 mg/dL; HbA1c -0.97%	35 trials; effect seen in type 2 diabetes	Psyllium

^{26 9}

●

Bifidobacterium abundance

Higher in trials

How much of a group of gut bacteria called Bifidobacterium is found in stool.

Low certainty

Results and what it means

Why it was measured

To see whether inulin feeds this bacterial group.

Statistical vs. clinical meaning

A change in gut bacteria numbers; not the same as a symptom or health benefit.

Safety implication

Gas and bloating can follow fermentable fibre.

Study	Result	People	Product
¹⁸	Increase with chicory inulin-type fructans; SMD 0.83 (95% CI 0.58 to 1.08)	50 studies, 2,525 people	Chicory-derived inulin-type fructans

¹⁸

●

Episodes of fecal incontinence per week

Lower with psyllium in trials

How often loose or liquid stool leaked each week.

Low certainty

Results and what it means

Why it was measured

To see whether a fibre supplement reduces leaking.

Statistical vs. clinical meaning

A clear fall with psyllium in one trial; another gel fibre made it worse.

Safety implication

Fullness and bloating led some people to stop.

Study	Result	People	Product
⁴	Estimated episodes per week: placebo 5.5, psyllium 2.5, gum arabic 4.3, carboxymethylcellulose 6.2	189 adults with fecal incontinence	16 g of fibre a day for 32 days (trial amount)

⁴

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 5

Dry swelling fibres can block the throat or gullet without enough fluid. Psyllium, methylcellulose and calcium polycarbophil all swell into a gel. A US federal rule (21 CFR 201.319) names all three, and says choking and gullet blockage have been linked to these gums and mucilloids when taken without enough fluid or by people with a narrowed gullet or trouble swallowing. Dry forms must carry a Choking warning and a direction to use a full glass (at least 8 ounces) of fluid. Case reports describe the gullet blocked after psyllium powder or granules, including in a man with Parkinson's disease and a woman who kept granules in her mouth first. The rule says people with trouble swallowing should not take these products. The rule is about labelling and is a regulator statement; it is not advice to take any fibre. Regulation and case report ^{28 22 21}
Bowel blockage. A case report describes bowel obstruction after psyllium taken without enough fluid. The EU herbal committee lists a narrowed stomach or gut, and failure to pass stool after a laxative, as reasons not to use ispaghula (psyllium) husk. MedlinePlus asks people with intestinal blockage to tell a doctor before psyllium. Similar statements for methylcellulose and polycarbophil were not read from health agencies, although the US rule groups them with psyllium. Case report and authoritative guidance ^{11 29 30 28}
Psyllium allergy, including from breathing in the powder. Psyllium is a known allergen. A review described reactions from airway symptoms on inhaling dust to anaphylaxis after swallowing, and reported one fatal case. In a plant that processed psyllium, 32% of tested workers had positive skin tests or raised IgE. MedlinePlus warns that breathing in the powder while mixing can cause allergic reactions. Allergy to methylcellulose, polycarbophil, inulin or wheat dextrin was not researched here. Case report and cross sectional ^{14 1 30}
Gas and bloating are the common problem. In the constipation meta-analysis, flatulence was higher with fibre (SMD 0.80). In an over-the-counter review, diarrhea, nausea, bloating and abdominal pain were common, with no serious adverse events reported in the trials. In the fecal incontinence trial, flatus, belching, fullness and bloating were somewhat higher on the full fibre amount, and people with more fullness or bloating were likelier to stop. Inulin is fermented, so gas is expected; the abstracts read gave no numbers for it. Meta analysis and randomised trial ^{33 20 3}
Fibre can change how other medicines are absorbed. MedlinePlus says not to take digoxin, aspirin (salicylates) or nitrofurantoin within 3 hours of psyllium. The EU committee says to keep ispaghula half an hour to an hour away from other medicines. A systematic review found limited evidence that fibre lowers levothyroxine absorption. A small 1987 trial found an ispaghula product did not change digoxin levels. Spacing advice for methylcellulose, polycarbophil, inulin and wheat dextrin was not read. A pharmacist can say how to space your own medicines. Authoritative guidance and trial ^{30 29 25 19}

Side effects 5

Effect	How often	Severity and recovery	Evidence
Gas, bloating and a feeling of fullness Fullness was the one symptom that differed from placebo with psyllium in the incontinence trial.	Flatulence SMD 0.80 versus control in the constipation meta-analysis.	Usually mild Not stated in the abstracts read.	Meta analysis and randomised trial ^{33 3}
Diarrhea, nausea, abdominal pain The review was funded by Bayer US.	Described as common in over-the-counter constipation trials; no number given.	Mild; no serious adverse events were reported in that review Not stated.	Systematic review ²⁰
Gullet (esophagus) blockage and choking Frequency is not given by any source read. Cases involve dry psyllium powder or granules, little liquid, or swallowing problems.	Not established	Serious Endoscopic removal was needed in the psyllium case read.	Case report and regulation ^{28 22 21}
Intestinal obstruction After psyllium taken without enough fluid.	Not established	Serious Treated without surgery in the case read.	Case report ¹¹
Allergic reactions including anaphylaxis (psyllium) How often this happens in the general public is unknown.	Not established	Serious One reported death in a published case.	Case report ¹⁴

Liver

No liver injury was found in the sources read. A liver-safety reference (LiverTox) was not opened.

How often. Not available.

Monitoring. No agency monitoring advice was found.

This is a safety connection. It is not evidence that Fibre supplements compared supports liver health.

Medicines and supplements 6

With	Why it matters	Importance	Evidence	What to do
Digoxin, aspirin (salicylates) and nitrofurantoin absorption	Fibre may bind or slow the absorption of medicines taken at the same time (a general idea, not shown for each drug here).	MedlinePlus tells readers not to take these within 3 hours of psyllium. A small 1987 trial in 14 older people found an ispaghula product did not change digoxin levels.	Authoritative guidance and rct Low certainty ^{30 19}	Ask a pharmacist about timing for your own medicines.
Other oral medicines in general absorption	A gel in the gut may slow how fast other medicines are absorbed (theory).	The EU herbal committee says to take ispaghula at least half an hour to an hour before or after other medicines.	Authoritative guidance Low certainty ²⁹	Ask a pharmacist; advice was read for psyllium only.
Levothyroxine (thyroid tablets) absorption	Fibre may reduce thyroid tablet absorption.	A 2021 systematic review found limited evidence of lowered absorption with fibre and advised spacing doses.	Systematic review Low certainty ²⁵	Keep a time gap and have thyroid blood tests checked with your doctor.
Diabetes medicines (insulin and tablets) pharmacodynamic	Psyllium lowered fasting glucose and HbA1c in trials; both together may lower blood sugar further.	Possible added lowering; no low-blood-sugar case was read.	Meta-analysis Low certainty ^{26 9}	Tell your doctor; they may want to monitor blood sugar.
Statins pharmacodynamic	Added LDL lowering with psyllium.	Extra LDL lowering in three trials (industry-linked authors).	Meta-analysis Low certainty ⁵	Do not change a statin without your doctor.
Methylcellulose, polycarbophil, inulin and wheat dextrin with medicines absorption	Not read.	No interaction study or agency statement for these four was read.	None found Not enough evidence	Ask a pharmacist before combining with medicines.

Who should check first 8

Situation	Advice	Evidence
Difficulty swallowing, throat problems or a narrowed gullet	The US rule says people with difficulty swallowing should not take these products, and the EU committee says not to use ispaghula husk with swallowing or throat problems.	Regulation and authoritative guidance ^{28 29 22}
Narrowing or blockage of the stomach or gut; no stool after a laxative	The EU committee says not to use ispaghula husk (psyllium); MedlinePlus asks people with blockage to tell a doctor first. See a doctor.	Authoritative guidance ^{29 30 11}
Rectal bleeding that has not been explained	The EU committee lists undiagnosed rectal bleeding as a reason not to use ispaghula husk; MedlinePlus asks people to tell a doctor about rectal bleeding.	Authoritative guidance ^{29 30}
Known psyllium allergy, or dust exposure at work	Avoid psyllium; workers handling powder had higher rates of sensitisation.	Case report and cross sectional ^{14 1}
Pregnancy	The EU committee page did not mention pregnancy, and no pregnancy safety study was read for any of the five fibres. Ask a doctor or pharmacist.	Gap ²⁹
Breastfeeding	LactMed says psyllium is not absorbed from the gut and is acceptable during breastfeeding. Nothing was read for the other four fibres.	Authoritative guidance ⁸
Children	No safety data in children were read for these fibres. Do not give a child a fibre supplement without a doctor or pharmacist's advice.	Gap
Kidney disease	MedlinePlus lists kidney disease among conditions to tell a doctor about before psyllium. No further detail was read.	Authoritative guidance ³⁰

Overdose, product quality and regulators

Animal. Not reviewed.

High dose or long term signals. No long-term safety data for the five fibres were read. MedlinePlus says not to use psyllium longer than 1 week unless a doctor says so; a regulator or label may differ for other fibres.

Overdose response. Not studied; blockage risk rises with too little fluid.

Genotoxicity. Not researched.

Contamination, additives and label accuracy of fibre supplements were not researched for this page.

Body	Action	Date
US Food and Drug Administration (21 CFR 201.319) (United States)	Names calcium polycarbophil, methylcellulose and psyllium (plantago seed) among water-soluble and hydrophilic gums and mucilloids. Says esophageal obstruction and asphyxiation have been linked to these products taken without enough fluid or by people with esophageal narrowing or trouble swallowing. Dry or incompletely hydrated oral forms must carry a Choking warning and a direction to take with at least 8 ounces (a full glass) of fluid. Granular psyllium forms are not generally recognised as safe and effective as over-the-counter laxatives and need an approved drug application. source	2007-03-29
MedlinePlus (US National Library of Medicine; AHFS patient information) (United States)	Describes psyllium as a bulk-forming laxative for constipation. Says to drink at least 8 ounces of liquid with it, not to use it longer than 1 week unless a doctor says so, to keep it 3 hours from digoxin, aspirin and nitrofurantoin, and to avoid breathing in the powder. Asks readers to tell a doctor about diabetes, heart disease, high blood pressure, kidney disease, rectal bleeding, intestinal blockage or trouble swallowing. source
EMA / HMPC (European Union)	Community herbal monograph on ispaghula (Plantago ovata) seed husk: habitual constipation, soft stools where straining hurts, more fibre in IBS with constipation. Warnings as listed in Safety. Revision 2 consultation closed 15/05/2024; page status 'ongoing call for scientific data'. source	2013-07-23
LactMed (US National Library of Medicine) (United States)	Psyllium is not absorbed from the gut and is acceptable during breastfeeding. source	2021-05-17

When to get medical help

Trouble swallowing, chest pain, vomiting or a feeling of food stuck after taking a fibre: seek emergency care (this is the US label warning).
Severe belly pain, swelling, vomiting, or no stool or gas: seek urgent care.
Hives, lip or throat swelling, wheeze or faintness: emergency care (possible anaphylaxis).
New rectal bleeding, or bleeding that does not stop: see a doctor.

Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

Which fibre supplement is best?

The sources read do not name a winner. Psyllium has the most trial evidence for constipation and cholesterol. No trial compared all five fibres.

^{33 16}

Does psyllium help constipation?

Yes, probably. In a 2022 meta-analysis of 16 trials, 66% of people on fibre responded versus 41% on control. The trials differed a lot, and gas was more common.

^{33 20}

Is methylcellulose better than psyllium?

Not shown. A small 2026 scan study in 22 healthy people found methylcellulose made more bowel water than psyllium. A 1988 study found both raised stool frequency in constipated people but did not show one beat the other.

^{6 10}

Does calcium polycarbophil work?

A review in older adults found it better than placebo for short-term constipation, and a small 1993 trial found 15 of 21 people with irritable bowel syndrome preferred it to placebo. The studies are small and old.

^{13 24}

Is inulin a laxative?

Reviews say it is not, because gut bacteria ferment it. A pooled analysis found it raised Bifidobacterium and helped bowel function in healthy people. Evidence for constipation was not found.

^{15 18}

Does wheat dextrin help constipation?

No trial of wheat dextrin alone was found. One small trial of a blend that included it helped, but the blend cannot be credited to wheat dextrin. A 2017 review says it is not a laxative.

^{7 16}

Does psyllium lower cholesterol?

Modestly. Two meta-analyses found LDL cholesterol lower by about 0.33 to 0.35 mmol/L. That is a lab marker, not proof of fewer heart attacks, and it is a psyllium result.

^{12 27}

Does fibre help irritable bowel syndrome?

A little, mainly soluble fibre such as psyllium or calcium polycarbophil, and mostly in IBS with constipation. It did not help abdominal pain, and bran did not help.

^{2 17 24}

Why must dry fibre be taken with fluid?

Swelling fibres can block the throat or gullet if taken without enough fluid. A US federal rule requires a Choking warning and a direction to use a full glass of fluid, and says people with trouble swallowing should not take them.

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Can fibre supplements affect my medicines?

They can. MedlinePlus lists digoxin, aspirin and nitrofurantoin for psyllium, and a review found limited evidence for levothyroxine. Ask a pharmacist about your own medicines.

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Are they safe in pregnancy, breastfeeding and for children?

LactMed says psyllium is acceptable during breastfeeding because it is not absorbed. No pregnancy or children's safety data were read for these fibres, so ask a doctor or pharmacist.

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Can psyllium cause an allergy?

Yes. Psyllium is a known allergen. Workers who handle the powder have higher rates of sensitisation, and a rare fatal anaphylaxis has been reported. MedlinePlus warns against breathing in the powder.

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-26
Last substantive update: 2026-10-26
How we research: We started from our existing fibre summary and the earlier psyllium page, then read the US labelling rule and MedlinePlus and re-read PubMed abstracts for reviews, meta-analyses and trials. Only abstracts were read for studies. The NHS and NCCIH pages could not be opened and are marked unread.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. Some trials were industry-linked or funded; this is flagged where stated.

Sources 33

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

Bardy JD, Malo JL, Séguin P et al.. Occupational asthma and IgE sensitization in a pharmaceutical company processing psyllium.. Am Rev Respir Dis. 1987. PMID 3579003. DOI 10.1164/arrd.1987.135.5.1033. (abstract)
Bijkerk CJ, Muris JWM, Knottnerus JA et al.. Systematic review: the role of different types of fibre in the treatment of irritable bowel syndrome.. Aliment Pharmacol Ther. 2004. PMID 14984370. DOI 10.1111/j.0269-2813.2004.01862.x. (abstract)
Bliss DZ, Savik K, Jung HJG et al.. Symptoms associated with dietary fiber supplementation over time in individuals with fecal incontinence.. Nurs Res. 2011. PMID 21543963. DOI 10.1097/NNR.0b013e3182186d8c. (abstract)
Bliss DZ, Savik K, Jung HJ et al.. Dietary fiber supplementation for fecal incontinence: a randomized clinical trial.. Res Nurs Health. 2014. PMID 25155992. DOI 10.1002/nur.21616. (abstract)
Brum J, Ramsey D, McRorie J et al.. Meta-Analysis of Usefulness of Psyllium Fiber as Adjuvant Antilipid Therapy to Enhance Cholesterol Lowering Efficacy of Statins.. Am J Cardiol. 2018. PMID 30078477. DOI 10.1016/j.amjcard.2018.06.040. (abstract)
Dellschaft N, Alhasani A, Reid JESJ et al.. Clinical Trial: Randomised Placebo-Controlled Trial of Methylcellulose and Psyllium Gels on Inulin-Induced Colonic Gas.. Aliment Pharmacol Ther. 2026. PMID 42728685. DOI 10.1111/apt.70964. (abstract)
Di Minno A, Morone MV, Buccato DG et al.. Combination of Dietary Fibers From Different Food Origins as a Treatment for Adults With Functional Constipation: A Randomized Clinical Trial.. Food Sci Nutr. 2026. PMID 42369644. DOI 10.1002/fsn3.72048. (abstract)
Drugs and Lactation Database (NICHD). Psyllium (LactMed entry). Drugs and Lactation Database (LactMed). 2021. PMID 30000405. (abstract)
Gibb RD, McRorie JW Jr, Russell DA et al.. Psyllium fiber improves glycemic control proportional to loss of glycemic control: a meta-analysis of data in euglycemic subjects, patients at risk of type 2 diabetes mellitus, and patients being treated for type 2 diabetes mellitus.. Am J Clin Nutr. 2015. PMID 26561625. DOI 10.3945/ajcn.115.106989. (abstract)
Hamilton JW, Wagner J, Burdick BB et al.. Clinical evaluation of methylcellulose as a bulk laxative.. Dig Dis Sci. 1988. PMID 2839321. DOI 10.1007/BF01535996. (abstract)
Hefny AF, Ayad AZ, Matev N et al.. Intestinal obstruction caused by a laxative drug (Psyllium): A case report and review of the literature.. Int J Surg Case Rep. 2018. PMID 30321826. DOI 10.1016/j.ijscr.2018.10.001. (abstract)
Jovanovski E, Yashpal S, Komishon A et al.. Effect of psyllium (Plantago ovata) fiber on LDL cholesterol and alternative lipid targets, non-HDL cholesterol and apolipoprotein B: a systematic review and meta-analysis of randomized controlled trials.. Am J Clin Nutr. 2018. PMID 30239559. DOI 10.1093/ajcn/nqy115. (abstract)
Kang SJ, Cho YS, Lee TH et al.. Medical Management of Constipation in Elderly Patients: Systematic Review.. J Neurogastroenterol Motil. 2021. PMID 34642269. DOI 10.5056/jnm20210. (abstract)
Khalili B, Bardana EJ Jr, Yunginger JW. Psyllium-associated anaphylaxis and death: a case report and review of the literature.. Ann Allergy Asthma Immunol. 2003. PMID 14700444. DOI 10.1016/S1081-1206(10)61538-4. (abstract)
McRorie JW, Chey WD. Fermented Fiber Supplements Are No Better Than Placebo for a Laxative Effect.. Dig Dis Sci. 2016. PMID 27680987. DOI 10.1007/s10620-016-4304-1. (abstract)
McRorie JW, McKeown NM. Understanding the Physics of Functional Fibers in the Gastrointestinal Tract: An Evidence-Based Approach to Resolving Enduring Misconceptions about Insoluble and Soluble Fiber.. J Acad Nutr Diet. 2017. PMID 27863994. DOI 10.1016/j.jand.2016.09.021. (abstract)
Moayyedi P, Quigley EM, Lacy BE et al.. The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis.. Am J Gastroenterol. 2014. PMID 25070054. DOI 10.1038/ajg.2014.195. (abstract)
Nagy DU, Sandor-Bajusz KA, Body B et al.. Effect of chicory-derived inulin-type fructans on abundance of Bifidobacterium and on bowel function: a systematic review with meta-analyses.. Crit Rev Food Sci Nutr. 2023. PMID 35833477. DOI 10.1080/10408398.2022.2098246. (abstract)
Nordström M, Melander A, Robertsson E et al.. Influence of wheat bran and of a bulk-forming ispaghula cathartic on the bioavailability of digoxin in geriatric in-patients.. Drug Nutr Interact. 1987. PMID 3038494. (abstract)
Rao SSC, Brenner DM. Efficacy and Safety of Over-the-Counter Therapies for Chronic Constipation: An Updated Systematic Review.. Am J Gastroenterol. 2021. PMID 33767108. DOI 10.14309/ajg.0000000000001222. (abstract)
Salguero Molpeceres O, Seijas Ruiz-Coello MC, Hernández Núñez J et al.. [Esophageal obstruction caused by dietary fiber from Plantago ovata, a complication preventable by adequate information].. Gastroenterol Hepatol. 2003. PMID 12681118. (abstract)
Shin S, Kim JH, Mun YH et al.. Acute esophageal obstruction after ingestion of psyllium seed husk powder: A case report.. World J Clin Cases. 2022. PMID 35321163. DOI 10.12998/wjcc.v10.i7.2336. (abstract)
Thirlby RC, Kelly R. Pectin and methyl cellulose do not affect intestinal function in patients after ileal pouch-anal anastomosis.. Am J Gastroenterol. 1997. PMID 8995946. (abstract)
Toskes PP, Connery KL, Ritchey TW. Calcium polycarbophil compared with placebo in irritable bowel syndrome.. Aliment Pharmacol Ther. 1993. PMID 8439642. DOI 10.1111/j.1365-2036.1993.tb00074.x. (abstract)
Wiesner A, Gajewska D, Paśko P. Levothyroxine Interactions with Food and Dietary Supplements-A Systematic Review.. Pharmaceuticals (Basel). 2021. PMID 33801406. DOI 10.3390/ph14030206. (abstract)
Xiao Z, Chen H, Zhang Y et al.. The effect of psyllium consumption on weight, body mass index, lipid profile, and glucose metabolism in diabetic patients: A systematic review and dose-response meta-analysis of randomized controlled trials.. Phytother Res. 2020. PMID 31919936. DOI 10.1002/ptr.6609. (abstract)
Zhu R, Lei Y, Wang S et al.. Plantago consumption significantly reduces total cholesterol and low-density lipoprotein cholesterol in adults: A systematic review and meta-analysis.. Nutr Res. 2024. PMID 38688104. DOI 10.1016/j.nutres.2024.03.013. (abstract)
. US Code of Federal Regulations, Title 21, section 201.319: required warnings and directions for water-soluble gums, hydrophilic gums and hydrophilic mucilloids (including calcium polycarbophil, methylcellulose and psyllium); last amendment shown 2007-03-29. . . (full-text)
. EMA/HMPC Community herbal monograph on Plantago ovata Forssk., seminis tegumentum (ispaghula husk), Revision 1. . . (summary-only)
. MedlinePlus Drug Information: Psyllium (AHFS patient information). . . (full-text)
. NCCIH: psyllium page. . . (not-found)
. NHS: ispaghula husk medicine pages. . . (not-found)
van der Schoot A, Drysdale C, Whelan K et al.. The Effect of Fiber Supplementation on Chronic Constipation in Adults: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials.. Am J Clin Nutr. 2022. PMID 35816465. DOI 10.1093/ajcn/nqac184. (abstract)

Where to buy

Check the label first. Whatever you buy, look for these:

The amount of the active ingredient per serving, not just the front-label claim
A third-party testing mark (USP, NSF or ConsumerLab)
Other ingredients and allergens
Ask a pharmacist about interactions with your medicines

Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.

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Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.