5–10 g with plenty of water, 1–3 times a day. Start low to avoid gas.
Lowers LDL cholesterol.
Smooths the postprandial blood sugar rise.
View the study (RCT) →⏱ 3 min read
Psyllium is the mucilaginous husk of the seeds of Plantago ovata, a plant native to India that produces a partially fermentable soluble fiber with physical and biological properties so distinctive that they make it one of the supplements with the best balance of evidence, safety, and cost in the entire modern natural pharmacopoeia: three teaspoons a day can do more for your colon, your cholesterol, and your blood sugar than many exotic supplements ten times more expensive.
When it comes into contact with water, psyllium forms a viscous gel that holds several times its weight in liquid, and this physical property explains a good part of its clinical effects: it increases stool bulk and softness, slows gastric emptying, traps bile salts in the intestinal lumen, and slows glucose absorption, four different mechanisms that translate into four clinical indications with clear evidence.
The most classic indication, and the one with the best immediate evidence, is chronic functional constipation: 5 to 10 grams of psyllium powder dissolved in water one to three times a day increase bowel movement frequency, improve consistency (Bristol scale closer to optimal), and reduce straining during defecation, comparably to or better than many over-the-counter laxatives, without the adverse effects of intestinal stimulants that should not be used chronically.
Paradoxically, psyllium also works in functional diarrhea and in diarrhea-predominant irritable bowel syndrome, because by absorbing water it firms up stools that are too loose; this bidirectional effect (regulating in both directions) distinguishes it from most treatments for bowel problems and makes it a very reasonable first-line option in any transit dysfunction.
Psyllium is one of the few supplements with consolidated evidence and approval by regulatory bodies (FDA, EFSA) for lowering LDL cholesterol: doses of 7 to 10 grams daily for 4 to 12 weeks reduce LDL by 5 to 10 percent consistently in large meta-analyses, an effect comparable to that of low doses of some statins or to that of phytosterols.
The mechanism combines the capture of bile salts in the intestinal lumen (which forces the liver to synthesize more bile salts from available cholesterol) with a reduction in the intestinal absorption of dietary cholesterol; the effect lasts as long as consumption continues and adds to that of statins in people who already take them, without generating relevant drug interactions.
In type 2 diabetes, taking 5 to 10 grams of psyllium with meals reduces the postprandial glucose peak by 20 to 30 percent and modestly improves HbA1c with prolonged use; the mechanism is physical (slowing of gastric emptying and glucose absorption) and combines with the effect on lipids to offer a very interesting metabolic profile in people with metabolic syndrome or incipient diabetes.
Effective doses range from 5 to 10 grams daily, divided into one to three servings, dissolved in at least 200 ml of water and taken immediately (because it becomes difficult to swallow as it gels) and followed by another glass of water to ensure passage to the stomach without risk of esophageal obstruction; it is advisable to start with low doses and increase gradually to avoid the gas and abdominal bloating typical of the first weeks.
Psyllium should be taken at least one hour apart from any oral medication because it may reduce its absorption through nonspecific adsorption; people with esophageal stricture, severe intestinal diverticula, or previous intestinal narrowing should be cautious because of the (rare) risk of impaction; prolonged consumption of psyllium without enough water can cause intestinal obstruction in extreme cases, a complication that is avoidable with adequate hydration.
Information, not medical advice. Scientific evidence reflects the quality of the studies.