The Health Benefits of Fiber Supplements

Help with Constipation, Diarrhea, IBS, IBD, and Diverticulosis

Fiber supplements are nutritional products that are available over the counter at drugstores, health food stores, big box stores, and online. They come in a variety of formulations, including capsules, powders, and baked goods and they contain one of three types of fiber—psyllium, methylcellulose, or polycarbophil.

Fiber supplements typically are taken to help maintain the healthy functioning of the digestive system, aid in weight loss, and help treat or prevent certain diseases and conditions. They generally are regarded as safe, but some fiber supplements can cause side effects, such as bloating or gas, especially if they are not taken according to directions.

Psyllium pills piled on each other
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Health Benefits

Fiber is a type of carbohydrate that's naturally found in fruits, vegetables, legumes, and whole grains. Fiber is important for maintaining regular bowel movements. Dietary fiber is also filling and it can be helpful for weight loss and maintenance.

Despite being so plentiful, most Americans do not eat enough of the foods that naturally contain fiber. Supplements can help people gain the many health benefits of fiber, which include helping maintain optimal blood sugar and cholesterol levels. Adequate fiber intake also is associated with preventing certain cancers, heart disease, diabetes, and food allergies.

For optimal health, the Academy of Nutrition and Dietetics recommends adult males get at least 38 grams (g) of fiber per day and females get 25 g of fiber per day.

Often, people take fiber supplements to help manage common digestive problems.

  • Diarrhea: Soluble fiber absorbs water as it passes through the digestive tract, transforming into a gel-like substance that helps slow digestion, making it especially useful for treating diarrhea.
  • Constipation: Insoluble fiber softens and adds bulk to stool so that it's easier to pass, which can help relieve constipation and prevent the formation of hemorrhoids and anal fissures that can result from passing hard stools.

Fiber supplements are sometimes included as part of an overall treatment plan for conditions such as irritable bowel syndrome (IBS) and inflammatory bowel diseases (IBD) including Crohn's disease, and ulcerative colitis. They should be used only with a healthcare provider's direction in these circumstances.

Possible Side Effects

The potential side effects of fiber supplements include:

  • Gas and pain from gas
  • Abdominal bloating
  • Lowered blood glucose
  • Diarrhea or constipation (if taken in excess)
  • Unwanted weight loss

Because of the way fiber supplements bulk up in the dietary contents in the intestinal tract and absorb surrounding materials, they can interfere with the body's ability to absorb medications, vitamins, and nutrients.

Dosage and Preparation

Fiber supplements come in a variety of formulations, including powders to be mixed with water or another liquid or capsules to be swallowed whole. Fiber is also often added to foods like crackers, cookies, cereals, and bars.

Dosage will vary based on the product and the desired effects. It's generally advisable to start with a low dose and build up until you've reached the recommended total daily fiber intake, which should always take into account your dietary sources of fiber.

Psyllium

Made from the seeds of a plant in the Plantago genus, psyllium contains 70% soluble fiber and 30% insoluble fiber. It breaks down in the gut (fermentation) as a food source for the "good bacteria." For this reason, it can cause gas.

Psyllium is used to treat constipation and IBS. It has roughly 20 calories per tablespoon. Brand names include Metamucil, Fiberall, Hydrocil, Konsyl, and Serutan.

Methylcellulose

This non-allergenic, non-fermentable fiber is created from the cell walls of plants. It's a soluble fiber that pulls in water to create a softer stool and often is used to treat constipation and some causes of diarrhea and maintain regular bowel movements.

It can be used long-term but it may interfere with the absorption of food and nutrients, so it should not be taken at the same time as some prescription medications. Methylcellulose is sold under the brand name Citrucel.

Polycarbophil

This soluble fiber absorbs water in the intestinal tract and creates a bulkier, softer stool. It does not ferment and is not absorbed by the body.

Polycarbophil may be used to treat constipation and bowel movement irregularities, but it is not appropriate for people who have difficulty swallowing. It should not be taken at the same time as medication. Polycarbophil is sold under the brand names FiberCon, Fiber Lax, Equalactin, and Mitrolan.

What to Look For

When shopping for fiber supplements, you'll want to make sure it contains the type of fiber you want. And some supplements have added sugar, salt, flavorings, or dyes you may want to avoid. For these reasons, make sure to check the ingredients listed on the packaging before making your purchase.

A Word From Verywell

Fiber supplements are available over the counter and are considered safe for most people. If you have a medical condition you think might improve by taking a fiber supplement, talk to your healthcare provider first. If you are experiencing diarrhea or constipation regularly, you may need to be evaluated for a digestive condition before starting to treat it with fiber.

Frequently Asked Questions

  • What foods are high in fiber?

    Among the richest sources of dietary fiber:

    • Cereal
    • Popcorn
    • Whole grains (especially bulgur, spelt, teff, barley, and oat bran)
    • Beans
    • Lentils
    • Vegetables (artichokes, canned pumpkin, cooked parsnips, winter squash, turnip greens)
    • Whole fruits and berries
    • Fresh vegetables (broccoli, Brussels sprouts, beets, and carrots)
    • Legumes (lentils, split peas, kidney beans, chickpeas, black beans, pinto beans)
    • Seeds (pumpkin, chia, sunflower, flax)
  • What's the best time of day to take a fiber supplement?

    Recommendations vary, but you may want to divide your dose into two or even three portions to take at evenly spaced intervals throughout the day. For example, the makers of Metamucil advise taking their product three times a day with meals. This can help prevent bloating and gas that sometimes occur as a result of taking a large dose all at once.

  • Is it OK to take a fiber supplement every day?

    For most healthy people, it is perfectly fine to take a daily fiber supplement and many people rely on them to make up for a lack of fiber in their diet. That said, it's always best to get nutrients from dietary sources, so if you need to boost your fiber intake, start by eating more fiber-rich foods.

  • Can I take a fiber supplement at the same time I take my other medications?

    In general, you should avoid taking your medications with your fiber supplements. Since a fiber supplement passes through the digestive system relatively quickly, a medication taken at the same time as a supplement can be excreted in your stool before your body has a chance to absorb it. Ask your healthcare provider about the ideal timing.

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14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Lyon M, Kacinik V. Is there a place for dietary fiber supplements in weight managementCurr Obes Rep. 2012;1(2):59-67. doi:10.1007/s13679-012-0016-9

  2. Liu L, Wang S, Liu J. Fiber consumption and all-cause, cardiovascular, and cancer mortalities: A systematic review and meta-analysis of cohort studies. Mol Nutr Food Res. 2015;59(1):139-46. doi:10.1002/mnfr.201400449

  3. Academy of Nutrition and Dietetics. Fiber.

  4. MedlinePlus. Soluble vs. insoluble fiber.

  5. Drugs.com. Fiber capsules side effects.

  6. McRorie J. Evidence-based approach to fiber supplements and clinically meaningful health benefits, part 1Nutr Today. 2015;50(2):82-89. doi:10.1097/nt.0000000000000082

  7. Jalanka J, Major G, Murray K et al. The effect of psyllium husk on intestinal microbiota in constipated patients and healthy controlsInt J Mol Sci. 2019;20(2):433. doi:10.3390/ijms20020433

  8. Drugs.com. Citrucel (methylcellulose) drug interactions.

  9. American Family Physician. Management of constipation in older adults.

  10. Drugs.com. Polycarbophil.

  11. United States Department of Agriculture. Dietary Guidelines for Americans. Food Sources of Dietary Fiber.

  12. Metamucil. Metamucil FAQS.

  13. University of California San Francisco. Increasing Fiber Intake.

  14. Harvard Health Publishing. Harvard Medical School. By the way doctor? Will a fiber supplement interfere with my medications?