Is psyllium better than other fibre for constipation?

Psyllium works for constipation, but it isn't clearly superior to other fibres — the trials that have compared it head-to-head show mixed results.

In a randomised trial of 72 people with chronic constipation, psyllium and a mixed soluble/insoluble plum-derived fibre produced similar improvements in complete spontaneous bowel movements per week 1. A crossover trial comparing psyllium (11 g twice daily) with dried prunes (50 g twice daily, same total fibre) found prunes outperformed psyllium on stool frequency and consistency 3. A smaller trial in older adults found psyllium at 24 g/day improved stool frequency and transit time compared with placebo 4.

Where psyllium has a practical edge is tolerability and versatility — it dissolves readily, has a mild taste, and its evidence base for IBS (soluble fibre class, NNT 7) is broader than most alternatives. Agave fructans showed comparable transit-time improvements in one small trial, though the numbers were too small to draw firm conclusions 2.

The honest summary: for simple constipation, food-first sources like prunes may perform as well or better, while psyllium remains a well-studied, convenient supplement option. Always take it with a full glass of water — dry use carries a documented choking risk — and separate it from any medications by at least 2 hours.