Psyllium is a soluble fiber used primarily as a gentle bulk-forming laxative in products such as Metamucil. It comes from a shrub-like herb called Plantago ovata that grows worldwide but is most common in India. Each plant can produce up to 15,000 tiny, gel-coated seeds, from which psyllium husk is derived.
The soluble fiber found in psyllium husks can help lower cholesterol. Psyllium can help relieve both constipation and diarrhea, and is used to treat irritable bowel syndrome, hemorrhoids, and other intestinal problems. Psyllium has also been used to help regulate blood sugar levels in people with diabetes. When psyllium husk comes in contact with water, it swells and forms a gelatin-like-mass that helps transport waste through the intestinal tract. Several large population based studies also suggest that increased fiber intake may reduce risk of colon cancer, but other studies have been conflicting.
After some promising early studies, newer results examining whether a high fiber diet protects against colon cancer have been mixed. Most large, well-designed studies have found only a slight association between fiber intake and colorectal cancer risk. In addition, fiber does not appear to protect against the recurrence of colorectal cancer.
Many well-designed studies have shown that psyllium relieves constipation. When combined with water, it swells and produces more bulk, which stimulates the intestines to contract and helps speed the passage of stool through the digestive tract. Psyllium is widely used as a laxative in Asia, Europe, and North America.
Studies suggest that a high-fiber diet may help lower insulin and blood sugar levels and improve cholesterol levels in people with diabetes. It may also reduce the chance of developing diabetes in those who are at risk.
Psyllium can also be used to help relieve mild-to-moderate diarrhea. It soaks up a significant amount of water in the digestive tract, making stool firmer and slower to pass.
Adding high fiber foods (such as psyllium-enriched cereals) to your diet may help lower heart disease risk. In fact, studies show that a diet high in water-soluble fiber is associated with lower triglyceride levels, and a lower risk of cardiovascular disease.
Your doctor may recommend psyllium to help soften stool and reduce the pain associated with hemorrhoids.
High Blood Pressure
Although studies are not entirely conclusive, adding fiber to your diet, particularly psyllium, may help lower blood pressure. In one study, 6 months of supplementation with psyllium fiber significantly reduced both systolic and diastolic blood pressure in overweight people with hypertension.
Soluble fibers, such as those in psyllium husk, guar gum, flax seed, and oat bran, can help lower cholesterol when added to a low-fat, low-cholesterol diet. Studies have shown psyllium can lower total, as well as LDL (bad) cholesterol levels, which may help reduce the risk of heart disease. In combination with cholesterol-lowering drugs, such as statins, psyllium provides an added benefit to reducing cholesterol levels.
Inflammatory Bowel Disease (IBD)
Although studies suggest conflicting results, some physicians recommend psyllium for mild-to-moderate cases of diarrhea from either ulcerative colitis or Crohn disease (another type of inflammatory bowel disorder). In one study of people with ulcerative colitis, psyllium was as effective as the prescription drug mesalamine (Pentasa, Rowasa, Asacol) in maintaining remission. However, for some people with IBD, too much psyllium can make symptoms worse. Work closely with your doctor to decide how much fiber is right for you.
Irritable Bowel Syndrome (IBS)
Several studies have found that soluble fiber (including psyllium) helps relieve some symptoms of IBS, such as diarrhea and constipation. Other studies, however, have found mixed results.
Studies and clinical reports suggest that psyllium may make you feel fuller and reduce hunger cravings.
This substance comes from psyllium seed and psyllium husk. Psyllium is also added to some cereals to increase fiber content.
Standard preparations of psyllium are available in dry seed or husk form, to be mixed with water as needed. Psyllium is an ingredient in some commercially-prepared laxatives. It also comes in capsules, tablets, and wafers.
How to Take It
Children should get fiber from their diet. Give a child psyllium supplements only under a doctor's supervision.
If you use a commercial product that contains psyllium, follow the package directions.
If you are not used to taking psyllium, it is best to begin with a low dose (such as 1/2 tsp. in an 8 oz. glass of water once a day), then gradually increase the dose as needed.
Your health care provider may recommend higher doses of psyllium to treat certain conditions. You can take psyllium first thing in the morning or before bedtime.
Because supplements may have side effects or interact with medications, you should take them only under the supervision of a knowledgeable health care provider.
Psyllium supplements may reduce or delay the absorption of certain medications (See Possible Interactions). As a rule, you should not take psyllium supplements at the same time as other medications. Take psyllium at least 1 hour before or 2 to 4 hours after taking other medications.
You should always take psyllium with a full 8 oz. glass of water, and you should drink at least 6 to 8 full glasses of water throughout the day to avoid constipation. Taking psyllium supplements without adequate liquids may cause it to swell, and, in extreme cases, cause choking.
DO NOT take this product if you have bowel obstructions or spasms, or if you have difficulty swallowing. People with esophageal stricture (narrowing of the esophagus) or any other narrowing or obstruction of the gastrointestinal tract should not take psyllium.
A potential side effect from any fiber product is gas and bloating.
People with kidney disease should talk to their doctor before taking psyllium.
If you are being treated with any of the following medications, you should not use psyllium supplements without first talking to your health care provider.
Antidepressant medications, Tricyclics
Dietary fiber has been shown to lower the blood levels and effectiveness of tricyclic antidepressant medications in some people. If you take tricyclic antidepressants, talk to your doctor before taking psyllium. Tricyclic antidepressants include:
- Amitriptyline (Elavil)
- Doxepin (Sinequan)
- Imipramine (Tofranil)
Taking psyllium with carbamazepine, a medication used to treat seizures, may decrease the absorption and effectiveness of carbamazepine.
Cholesterol-lowering medications (bile acid sequestrants)
Taking psyllium with cholesterol-lowering medications called bile acid sequestrants may help further lower cholesterol levels and may reduce side effects of colestipol. Talk to your doctor about whether this may be an option for you. Bile acid sequestrants include:
- Cholestyramine (Questram)
- Colestipol (Colestid)
Fiber supplements may reduce levels of blood sugar, making the possibility of hypoglycemia (low blood sugar) more likely. Talk to your doctor before taking fiber supplements, as your dose of diabetes medications may need to be adjusted.
Fiber supplements may reduce the absorption of digoxin, a medication used to regulate heart function. You should not take fiber supplements at the same time as digoxin.
Psyllium may lower lithium levels in the blood, reducing the effectiveness of this medication. If you are taking both psyllium and lithium, you should take them at least 1 to 2 hours apart, and your doctor should closely monitor your lithium levels.
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- Last reviewed on 10/19/2015
- Steven D. Ehrlich, NMD, Solutions Acupuncture, a private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.
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