What it is
Psyllium (SILL-ee-yum) supplements are derived from the seeds and seed husks of plants from the genus Plantago. Psyllium is very high in soluble fiber, which accounts for the many ways it is beneficial for digestive health. Consumers rely on psyllium primarily for constipation, but it can also help treat diverticular disease and irritable bowel syndrome. In addition, this supplement eases diarrhea by normalizing bowel function, reduces cholesterol levels, promotes weight loss, and may lower the risk of colon and breast cancers.

How it works
Psyllium is rich in both fiber and mucilage. Psyllium’s mucilage expands tenfold upon contact with water to form a gel. This gel serves to keep the feces soft and bulky, making them easier to pass. Psyllium’s laxative effect is mild enough to be used on an ongoing basis, generally leading to a bowel movement within 12 to 24 hours. Conversely, because psyllium adds bulk to the stool, it also helps resolve diarrhea symptoms.

Although numerous clinical trials have shown that psyllium lowers cholesterol levels, the exact mechanism of this action is not understood. It may be related to decreased cholesterol absorption, as well as to altering levels of the enzymes that process cholesterol.

Psyllium may also have a role in reducing the risk of colon and breast cancers. How it does so is still not clear, but it may be related to the way the herb binds to and removes toxins that initiate cancer and chemicals that promote its growth (for example, hormones). Psyllium has a mechanical “sweeping” action that removes waste matter stuck in folds and crevices of the large intestine.

Psyllium’s effectiveness for treating constipation is undisputed. However, how helpful psyllium will be with an individual case of constipation depends on the cause. One study of 149 constipated adults found that psyllium provided relief for 85 percent of those who had common constipation unrelated to a disease, but only 37 percent of people responded who were constipated because of a condition such as rectocele or internal prolapse (American Journal of Gastroenterology, 1997, vol. 91, no. 1).

In 1997 the Food and Drug Administration allowed foods or supplements that provide psyllium to make the health claim that psyllium reduces the risk of heart disease. Clinical trials confirm that psyllium lowers total cholesterol and LDL cholesterol, leading risk factors for heart disease. In most of the research, psyllium lowered cholesterol levels by 5 percent to 10 percent (Alternative Medicine Review, 2002, vol. 7, no. 2).

Psyllium also shows promise in clinical research for weight loss. In one study of 14 adults, about 7 grams of psyllium taken before a meal lessened hunger feelings and reduced the amount of food eaten (European Journal of Clinical Nutrition, 1998, vol. 52, no. 4).

Side effects
Although psyllium is gentle and safe enough to be used every day, an exceedingly small number of people are allergic to it (Annals of Allergy, Asthma & Immunology, 2003, vol. 91, no. 6). This is more likely if you have asthma or other allergies. Rare but severe psyllium allergies have been documented; consult a physician if you develop skin rash or experience difficulty breathing after taking psyllium.

How to take it
Psyllium seeds and seed husks are available in three main forms: powder or granules (mixed with water or juice), capsules, and wafers. All three forms should be taken with plenty of water or juice (at least 8 ounces) so the psyllium is able to work properly. Another option is to choose a breakfast cereal that contains psyllium. Recommended doses are as follows. Powder or granules: Take 1 teaspoon three times per day, stirred into an 8-ounce glass of water or juice. However, follow label directions; some products contain other ingredients that require a greater amount of psyllium to achieve an effective dose. Drink the mixture immediately because the psyllium will start to thicken in the glass. Capsules: Take one to three. Wafers: Two generally make an effective dose.

Psyllium is one of the least expensive supplements. Used daily, it can cost less than $3 per month. If you take it only occasionally to treat constipation, psyllium costs just 10 cents per use in powder form, 20 to 70 cents per use for capsules, and 40 cents per use for wafers.

Oregon-based freelancer Victoria Dolby Toews, MPH, is the author of User’s Guide to Sexual Satisfaction (Basic Health, 2003) and User’s Guide to Glucosamine and Chondroitin (Basic Health, 2002).