Compound or practice · Nutrition

Psyllium Husk

The most boring A-grade on the shelf: a soluble fiber that improves regularity, LDL, and glucose — and binds your medications.

Overall grade: Grade A
Last revised: Jul 10, 2026; 3
graded outcomes: 0
references listed

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A structured monograph in Prometheus's bundled library. Its grades are the monograph's own reading of the evidence, not a peer-reviewed review.

3 at grade A · 1 at grade B — 4 graded rows

What is known

Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.

Outcome	Grade	Effect size	Agreement
Constipation / regularityWell established	Evidence grade A	Moderate	high
LDL cholesterolBile-acid binding	Evidence grade A	Small	high
Post-meal glucoseSlows absorption	Evidence grade B	Small	high

Constipation / regularityEvidence grade A
Well established
Moderatehigh
LDL cholesterolEvidence grade A
Bile-acid binding
Smallhigh
Post-meal glucoseEvidence grade B
Slows absorption
Smallhigh

Conditions

How the entry reads its effect on diagnosed conditions: the direction first, then the grade. Never a substitute for the person who treats you.

IBS / constipation ImprovesEvidence grade ASoluble fiber first-lineGrade A

What is uncertain

Read off the same rows as above. Nothing here is added that the entry does not itself record.

Watch with Berberine: Slows berberine uptake — separate by 2 hours.

Interactions

Documented pairings with supplements and medicines. A medicine on this list is a conversation for whoever prescribes it.

LevothyroxineMind the timing
Fiber gel binds the dose — separate by 4 hours.
BerberineMind the timing
Slows berberine uptake — separate by 2 hours.

The evidence in words

What it is

Psyllium is a viscous soluble fiber from Plantago seed husks, one of the best-evidenced fiber supplements.

How it works

It forms a gel that normalizes stool (both constipation and diarrhea), slows carbohydrate absorption, and binds bile acids, lowering LDL cholesterol.

What the evidence shows

Grade A across several outcomes: it improves constipation and IBS symptoms, lowers LDL cholesterol (an FDA-recognized heart-health claim), and blunts post-meal glucose. Cheap, food-based, and genuinely useful — the catch is that its gel binds many oral drugs if taken together.

How to use it

5–10 g/day with plenty of water, building up slowly to limit gas. Separate from medications by ~2–4 hours.

Safety & interactions

Very safe; take with adequate fluid to avoid choking/obstruction. Introduce gradually to reduce bloating. levothyroxine — Fiber gel binds the dose — separate by 4 hours. Berberine — Slows berberine uptake — separate by 2 hours.

Bottom line

A rare supplement that helps bowels, cholesterol, and blood sugar at once. 5–10 g/day with water — just don't take it at the same time as your pills.

How it is used

As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.

Standard: 5–10 g/day with water; separate from meds by 2–4 h.

Entries that share this one's tags or conditions.

Beta-GlucansTwo different molecules under one name: oat beta-glucan reliably lowers LDL; yeast/mushroom beta-glucan modulates immunity.Evidence grade B
Psyllium Husk for Constipation / regularityEvidence grade A — Well establishedEvidence grade A
Psyllium Husk for IBS / constipationEvidence grade A — Soluble fiber first-lineEvidence grade A
Psyllium Husk for LDL cholesterolEvidence grade A — Bile-acid bindingEvidence grade A

Sources

This entry lists no references of its own.

Last revised Jul 10, 2026. A grade is this entry's reading of the evidence, not medical advice.