Fiber Supplements
Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.
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Sources of dietary fiber include fruits, vegetables, whole grains, legumes, and beans. The American Heart Association (AHA) recommends that at least half of daily grain intake come from whole grain foods.2 Dietary fiber can be divided into 2 basic categories: soluble and insoluble.
- Soluble fiber slows digestion and assists the body in absorbing vital nutrients from foods.3,4 It dissolves in the water found in the large intestine and forms a gel.3,4 This form of fiber can aid in lowering total cholesterol levels and low-density lipoprotein cholesterol levels, as well as improve glycemic index in patients with diabetes.1-3 Foods high in soluble fiber include oat bran, barley, peas, rice bran, beans, apple pulp, citrus fruits, strawberries, and psyllium husk.2,4
- Insoluble fiber does not dissolve in water, but it increases the movement of waste through the intestinal tract.3,4 Insoluble fibers have been associated with decreased cardiovascular risks and slow progression of cardiovascular disease, particularly in high-risk individuals.1,2 In addition to preventing constipation, this type of fiber may also aid in removing toxic waste in the colon. Foods high in insoluble fiber include wheat bran, whole grains, rice, flax seed, nuts, popcorn, cabbage, beets, carrots, Brussels sprouts, turnips, cauliflower, and apple skin, as well as other fruits and vegetables with skins.2,4
Adequate intake of dietary fiber is the most recommended choice for both the prevention and treatment of constipation and also has an important role in the maintenance of normal bowel function. In addition, various studies have demonstrated that an increased intake of fiber can promote various health benefits and possibly prevent or reduce various chronic health problems.1 Examples include lowering the risk of developing hemorrhoids or diverticulosis, aiding in the management of irritable bowel syndrome, promoting better management of glucose levels in patients with diabetes, promoting weight loss, and restoring regularity for individuals on low-carbohydrate diets.1-3 In addition, adequate fiber intake may aid in lowering cholesterol levels and blood pressure, as well as decreasing the risk of colon cancer.1-3
Many patients still find it difficult to consume the American Dietetic Association's recommended intake of dietary fiber; thus, some individuals elect to use the various fiber products on the market to supplement their dietary fiber intake and to maintain normal bowel function to prevent or reduce episodes of constipation. Fiber products on the market may contain various fiber sources that include wheat dextrin, methylcellulose, psyllium husk, inulin, and calcium polycarbophil. Pharmacists can provide essential guidance to patients regarding the proper selection of fiber supplements and can ensure that patients use these products correctly according to the manufacturers' recommendations. Currently, fiber supplements are available in a variety of dosage formulations, such as shakes, chewable tablets, wafers, and powders in several different flavors (Table). Many powder formulations can be mixed with 4 to 8 ounces of water or noncarbonated beverage or in soft foods such as apple sauce. Some fiber supplements contain calcium and vitami ns/minerals. Patients should be advised to read labels of fiber supplements to avoid the possibility of therapeutic duplications.
Role of the Pharmacist
When assisting patients in the selection of fiber supplements, pharmacists should remind patients to gradually increase fiber intake over time to avoid or reduce the incidence of adverse effects, such as intestinal flatulence, bloating, diarrhea, and cramping. The increase should be gradual over a few weeks, and, if possible, patients should also increase water intake. Inadequate fluid intake may decrease efficacy of the product and may cause intestinal or esophageal obstruction.5 Many manufacturers of fiber supplements have reminders on the product label that typically recommend taking fiber supplements with 8 ounces of water to avoid choking.6-8 Patients with preexisting medical conditions, such as those who must restrict fluid intake (eg, patients with renal dysfunction, congestive heart failure)3 and those currently taking any medications should discuss the use of these supplements with their primary health care provider prior to using these products.
Furthermore, because fiber supplements can decrease the absorption of many medications, patients should always be advised to take supplements 2 to 3 hours before or after other medications and to report any concerns to their physician. Patients should also be reminded that the use of fiber supplements should never be a substitute for a fiber-rich diet that contains other essential vitamins and minerals necessary for health. It is important to remind patients to try to obtain most of their daily intake of fiber through dietary means.
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References
- Marlett JA, McBurney MI, Slavin JL. Position of the American Dietetic Association: health implications of dietary fiber. J Am Diet Assoc. 2002;102(7):993-1000. www.adajournal.org/article/S0002-8223(02)90228-2/fulltext.
- Fiber. American Heart Association Web site. www.americanheart.org/presenter.jhtml?identifier=4574. Accessed September 30, 2008.
- Rollins CJ. Functional and Meal Replacement Foods. In Berardi RR, ed. Handbook of Nonprescription Drugs. 15th ed. Washington, DC: American Pharmacists Association; 2006:484-485.
- Soluble vs. Insoluble Fiber. MedlinePlus Web site. www.nlm.nih.gov/medlineplus/ency/article/002136.htm. Accessed September 30, 2008.
- Curry CE, Butler DM. Constipation. In Berardi RR, ed. Handbook of Nonprescription Drugs. 15th ed. Washington, DC: American Pharmacists Association; 2006:305-309.
- Metamucil Product Information. Metamucil Web site. www.metamucil.com. Accessed September 30, 2008.
- Fibercon Product Information. Fibercon Web site. www.fibercon.com. Accessed September 30, 2008.
- The Fiber Chronicles: Answers to Your Questions. Citrucel Product Information. www.citrucel.com/Ch5_FAQ.aspx#crush. Accessed September 30, 2008.
