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Psyllium husk

Also known as: Ispaghula, Plantago ovata, Metamucil

A soluble fiber that forms a gel in water. Strong evidence for regularity and lowering LDL cholesterol.

Common forms: Powder · Capsules · Wafers

Draft summary, not yet reviewed by a qualified health professional · Last updated 2026-11-03

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This information is for education only and is not medical advice, diagnosis, or treatment. Supplements can interact with medications and health conditions. Check with your doctor or pharmacist before starting anything, especially if you take medication, are pregnant or breastfeeding, or have a health condition. These statements have not been evaluated by the FDA; supplements are not intended to diagnose, treat, cure, or prevent any disease.

What the evidence says

Regularity

AStrong evidence

A meta-analysis of randomized trials found fiber supplements — psyllium in particular, at doses above 10 g/day for at least 4 weeks — improved chronic constipation.

Dose used in studies
>10 g/day, with plenty of water
Time to effect
1–4 weeks
Studies (2)

Heart health markers

AStrong evidence

A meta-analysis found about 10 g/day of psyllium lowered LDL cholesterol by roughly 13 mg/dL, along with non-HDL cholesterol and apolipoprotein B.

Dose used in studies
~10 g/day
Time to effect
3–6 weeks
Studies (1)

Gut comfort

BModerate evidence

Network meta-analysis found soluble fiber (mainly psyllium) improved global IBS symptoms.

Dose used in studies
Start ~3–5 g/day and increase gradually to 10–20 g/day
Time to effect
2–6 weeks
Studies (2)

Safety

Common side effects

  • Gas
  • Bloating (start low, go slow)

Avoid or ask your doctor first if

  • You have difficulty swallowing or a history of bowel obstruction
  • Always take with a full glass of water

Pregnancy & breastfeeding

Likely safe at normal dietary doses — confirm with your provider.

Medication interactions

  • moderateLithium: May reduce lithium absorption.
  • minorDiabetes medications: May lower blood sugar after meals; monitor levels.
  • minorThyroid medication: May reduce absorption of other oral medications — take them 2 hours apart.

This list covers common medication classes only and is not exhaustive.

Buying tips

Look for third-party testing seals (USP Verified, NSF Certified, or Informed Choice) and match the form and dose used in studies.

Where to buy (affiliate)

Further reading