Fiber Supplements, Fiber Laxatives

What Are Fiber Supplements?

Fiber supplements contain dietary fiber or synthesized fiber-like substances that increase bulk of the stool. They mostly contain indigestible carbohydrates. Several types and brands exist. They are available over the counter (OTC) in various forms, including powder, granules, seeds, chewable gum, caplets, wafers and capsules.

General Advice About Fiber Supplements

1. If you have persistent constipation not responding to high-fiber diet or persistent diarrhea after gallbladder, stomach or colon removal, then you can try fiber supplements, since they act as laxatives. If you have hemorrhoids or diverticulosis, you can try high-fiber diet, rather than supplements, to soften the stool. Other commonly advertised effects of fiber supplements, as weight loss or drop in blood cholesterol, should be achieved with appropriate diet; supplements alone are not likely to help. Despite the opposite claims, there is no firm proof about protecting role of fiber supplements against any type of cancer.

2. Do not take fiber supplements if you have suspected or confirmed intestinal obstruction. Do not offer fiber supplements to young children without doctor approval. Discuss with your doctor about taking supplements in diabetes, kidney disease, phenylketonuria, other chronic diseases or during pregnancy or lactation.

3. Soluble fiber supplements, like Psyllium husk, may help in both constipation and mild diarrhea, but they can cause bloating and flatulence. Insoluble fiber supplements, like cellulose, may help in constipation, do not cause gas but can cause diarrhea.  Read about properties of soluble and insoluble fiber.

4. Choose bland, unsweetened supplements, since added sorbitol, fructose, HFCS, aspartam or other additives may trigger diarrhea, especially if you have fructose malabsorption or IBS.

5. Some products are labeled as organic fiber supplement but often lack any certificate. Even those certified may contain substances that can irritate your bowel, so always carefully check the ingredients.

6. Recommended daily amount of fiber is about 20 g for children and women, and 30 g for men. Try to achieve this amount with high-fiber diet before considering fiber supplements.

7. Take fiber with sufficient amount of water or other soft, non-carbonated drink to prevent choking or constipation. Start with small amount of fiber and then increase it gradually to prevent bloating and gas.

8. If a fiber supplement does not ease diarrhea or constipation in 7-14 days, it will probably not help later.

Unwanted Side Effects of Fiber Supplements

So far, there is no firm proof that long-term use of fiber supplements would be harmful for healthy people. A downside of supplements is that they often contain no vitamins and minerals as regular plant foods do.

Soluble Fiber Supplements


Soluble fiber slows down stomach emptying and the passage of food through the gut, so it can prevent quick stomach emptying (dumping syndrome). It gives bulk to the stool, so it can prevent constipation. It absorbs water from the intestine, so it can prevent mild diarrhea. It binds some bile acids constantly released into intestine after gallbladder removal, so it can prevent bile salts diarrhea. Friendly intestinal bacteria may break down a certain amount of soluble fiber and some of resulting substances can be absorbed; it means soluble fiber supplements usually have some calories.

Side Effects

Soluble fiber yields gas and may cause bloating and flatulence. Choking or severe constipation is possible, if fiber is not ingested with sufficient amount of fluid. It can hamper absorption of cholesterol- or glucose-lowering drugs, digoxin, penicillin and antidepressants, vitamins, calcium or magnesium, especially in young children. It can aggravate gastroparesis (slow gastric emptying). Because of its laxative effect, soluble fiber may cause loose stools.

NATURAL Soluble Fiber Supplements

  • Psyllium husk (should be gluten-free). Examples: Metamucil®, Fiberall®, Hydrocil®, Konsyl®, Serutan®…
  • Pectin is produced from peels and pulp of citrus fruits (grapefruits or oranges) and apples. Various supplements are available.
  • Beta-glucan lowers LDL cholesterol and helps in excretion of bile acids. Example: Barliv®
  • Guar gum, derived from cluster beans, contains galactomannan, an indigestible carbohydrate. Example: Sunfiber®
  • Acacia fiber or gum arabic is derived from sap of Acacia senegal tree. Various products exist.
  • Wheat dextrin is soluble fiber but does not thicken and does not produce much gas. Example: Benefiber®
  • Inulin is a common name for oligosaccharides  (fructans) extracted from chicory roots or Jerusalem artichokes. Example: FiberChoise®. It may cause bloating and diarrhea in sensitive people and those with fructose malabsorption.
  • PGX (polyglycoplex) fiber is derived from the root of konjac plant. It can absorb water up to 200 times its own weight.


These fiber usually do not cause gas:

  • Methyilcellulose: Citrucel®
  • Polycarbophil: Fibercon®, Fiber-Lax®, Equalactin®, Mitrolan®

Insoluble Fiber Supplements

Insoluble fiber speeds up peristalsis and gives bulk to the stool, so it can prevent constipation. It does not contain calories and does not cause gas, but it can trigger diarrhea in sensitive people.

NATURAL Insoluble Supplements

  • Flax seed or linseed contains lignin, an insoluble fiber, and also a certain amount of soluble fiber. Supplements are in a form of whole or crushed seeds. Flax seed also contains lignan that can interfere with estrogen metabolism and can prevent hot flashes.
  • Cellulose: Unifiber® contains pure cellulose.

Resistant Starch

Resistant starch is derived from oats or barley. It is insoluble but is broken down by colonic bacteria and supposedly good for colonic health. Example: Hi-maize®.

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About Jan Modric (209 Articles)
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