psyllium
Meaning of psyllium: Seed husks that soak up water and turn stool into a soft gel, working by physics rather than by prodding the bowel.
Definition of psyllium
Psyllium is the husk of the seed of Plantago ovata, a plant grown mainly in India, sold as a powder, granules or capsules and swallowed with plenty of water. The husk is rich in soluble fiber that absorbs many times its own weight in liquid and forms a gel. That gel adds bulk and softness to stool and helps it move through the large bowel.
How does it work?
Psyllium is not absorbed and does not stimulate anything. Its fibers are long chains of sugar units arranged so that water is trapped between them. In the bowel the husk swells into a soft gel that holds water inside the stool rather than letting it be reabsorbed. Larger, softer, wetter stool stretches the bowel wall gently, and that stretch is itself the signal that prompts the muscle to push. The same gel firms up stool that is too loose, which is why the substance is used at both ends of the problem.
How does it compare with other laxatives?
| Type | How it acts | Speed |
|---|---|---|
| Bulk-forming, such as psyllium | Holds water in stool | Over days |
| Osmotic | Draws water into the bowel | A day or more |
| Stimulant | Prompts the bowel wall to contract | Hours |
| Lubricant or softener | Coats or wets the stool | Slow and modest |
As a bulk-forming laxative it is the slowest of these to act and the one that most closely imitates the effect of dietary fiber.
What else is it used for?
Soluble fiber binds bile acids in the small bowel and carries them out instead of letting them be recycled. The liver then pulls cholesterol from the blood to make replacements, and total cholesterol falls modestly. Psyllium is also used to firm loose stool in diarrhea and after some bowel operations, and it slows the rate at which sugar is absorbed from a meal.
What can go wrong?
Taken with too little fluid the husk can swell before it has passed through and lodge in the gullet or the digestive tract, and blockage has been reported. Bloating and wind are common in the first week and usually settle. The gel can also slow the absorption of other medicines taken at the same moment. Inhaling the dry powder repeatedly, as workers handling it may, can provoke allergic reactions.
Also known as
Used in a sentence
The regimen included psyllium as a bulk-forming agent for chronic constipation.
Good to know
Psyllium is a bulk-forming agent rather than a stimulant, and it needs adequate fluid to work, since the swollen husk can otherwise obstruct.
Word origin
Where “psyllium” comes from
From the Greek psylla, meaning flea, a reference to the small dark seeds.