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Psyllium (ispaghula husk)

The all-rounder of fibre supplements — proven for cholesterol, blood sugar and both constipation and loose stools.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsFiberSoluble fibreCholesterolGut

Psyllium is the husk of Plantago ovata seeds. It forms a thick gel in water, and of all the fibre supplements it has the deepest evidence base — which is why it’s the usual first choice.

Key takeaways

  • Lowers LDL cholesterol dose-dependently; recognised by the FDA heart-health claim at ~7 g/day of soluble fibre from psyllium.1
  • Normalises stool both ways — bulks and softens in constipation, firms up in diarrhoea (it’s a gel, not a stimulant).2
  • Modestly improves post-meal blood sugar and satiety.
  • Take with plenty of water and separate from medicines by ~2 h (it can slow their absorption).

What it is

A gel-forming (viscous) soluble fibre from psyllium seed husks. The gel is what does the work — trapping bile acids and cholesterol, slowing carbohydrate absorption and giving stool a soft, formed bulk.

The evidence

Meta-analyses show psyllium reduces LDL and total cholesterol in a dose-dependent way, underpinning an approved heart-disease-risk claim.1 It is a first-line, well-tolerated treatment for chronic constipation and helps IBS symptoms; because the gel holds water it also firms up loose stools.2

Dose

Start at 5 g once daily with a large glass of water and build up to 10–15 g/day in divided doses. For cholesterol, aim for ~7–10 g/day. Always take with enough fluid.

Safety

Very safe. Take with ample water (dry powder can obstruct the throat/oesophagus). It can reduce absorption of medicines — take drugs 1–2 h apart. Expect a little extra gas at first; increase the dose gradually.

Bottom line: the fibre supplement to reach for first — proven for cholesterol, blood sugar and bowel regularity, cheap and safe when taken with water.

References

Adult research summary for education, not a prescription.

  1. U.S. FDA health claim: soluble fibre from psyllium husk and reduced risk of coronary heart disease (21 CFR 101.81). www.ecfr.gov
  2. Jovanovski E, et al. Effect of psyllium fibre supplementation on LDL cholesterol: a systematic review and meta-analysis of RCTs. Am J Clin Nutr 2018. pubmed.ncbi.nlm.nih.gov

This article summarises nutrition science for education. It is not a substitute for individual medical advice; consult a professional before starting a supplement, in pregnancy, or alongside medication.