The Health Benefits of Fiber Supplements

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

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

Fiber supplements typically are taken to help maintain 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, if not taken according to directions.

Psyllium pills piled on each other
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Health Benefits

Fiber is a type of carbohydrate that occurs naturally in fruits, vegetables, legumes, and whole grains. Despite being so plentiful, most Americans do not eat enough of the foods that naturally contain fiber.

Supplements can help people to enjoy the many health benefits of fiber, which include helping to 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 men get at least 38 grams (g) of fiber per day and women get 25 g of fiber per day.

Most often, people take fiber supplements to help manage certain digestive problems. 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.

Insoluble fiber softens and adds bulk to stool so that it's easier to pass, and therefore can help relieve constipation, as well as prevent hemorrhoids and anal fissures that can result from passing hard stools. Adequate fiber also is important for maintaining regular bowel movements. Fiber is filling and can be helpful for weight loss and maintenance.

Fiber supplements are sometimes included as part of an overall treatment plan for conditions such as irritable bowel syndrome (IBS), inflammatory bowel diseases (IBD) including Crohn's disease and ulcerative colitis, and diverticulosis. 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 intestinal tract and absorb surrounding materials, they can interfere with the body's ability to assimilate 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, capsules to be swallowed whole, and 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 of fiber and build up until you've reached the recommended total daily fiber intake which should include your dietary sources of fiber, as mentioned below.


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, irritable bowel syndrome (IBS), and diverticulosis. It has roughly 20 calories per tablespoon. Brand names include Metamucil, Fiberall, Hydrocil, Konsyl, and Serutan.


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 may interfere with absorption of food and nutrients and so should not be taken at the same time as some prescription medications. Methylcellulose is sold under the brand name Citrucel.


Similar to methylcellulose, this soluble fiber also 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 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, though, 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 are:

    • 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?

    There's no evidence for most healthy people that taking a daily fiber supplement is harmful and many people do 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?

    It may not be ideal. Since a fiber supplement passes through the digestive system considerably faster than foods, including those rich in dietary fiber, it's possible a medication taken at the same time as a supplement will be excreted along with it 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.
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