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How Do I Add a Fiber Supplement?

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Posted by Benjamin Krevsky, MD, MPH

Here are some fiber questions that I often get from my patients: “My doctor suggested that I add a fiber supplement to my daily routine. I took a look at the fiber aisle in the drug store and was overwhelmed by the choices. How can I possibly choose?” “What are the benefits and problems with each type of fiber?” “Should I use a soluble fiber or insoluble fiber?” “Powders or pills?”

Why Add a Fiber Supplement?

Health care providers will often suggest the addition of fiber to a patient’s diet. This can help with constipation, diverticulosis, diarrhea, irritable bowel syndrome, heart disease, and diabetes among other health issues.

So What’s the Problem with Dietary Fiber?

While getting natural fiber from food would be ideal, adding high fiber foods such as beans, bran, and nuts can have side effects. First of all, one has to eat a lot of them to reach the usual goal of about 30 gm of dietary fiber/day. And everyone’s diet changes daily, so it is hard to be consistent. Also, many natural foods with high fiber content make people really gassy and bloated.

What Is the Difference Between Soluble & Insoluble Fiber?

Some fiber supplements are mostly soluble fiber, some mostly insoluble fiber, and others contain a mixture. Soluble fibers are able to dissolve in water, and are helpful in many ways. They delay digestion to help regulate sugar absorption, bind with fatty acids, and help lower LDL (bad) cholesterol. Insoluble fibers don’t dissolve in water, but help move along intestinal contents and hydrate the stool. This can help with constipation or irritable bowel syndrome.

Which Is Better, Capsules, Tablets, or Powders?

It doesn’t really matter which form the fiber comes in. Some people like powders, others are put off by them. The important thing to know is how many grams of fiber are in each form. For example, a teaspoon of psyllium husk powder has about 3.4 grams of fiber, while a capsule of the same fiber only has 0.4 grams of fiber. So it would take 8 psyllium capsules to get the same fiber as 1 teaspoon of psyllium powder. And that is still only 10% of the recommended dose of 30 grams/day. So getting fiber in the diet is still very important.

What Kinds of Fiber Are There?

The most commonly used fiber supplement is psyllium. It comes from the husk of the psyllium plant seed and contains both soluble and insoluble fibers. It is available in both capsules and powders. The powders are mixed with water, and can get thick and gelatinous. Also, because the fiber is natural, the bacteria in the colon ferment it, possibly leading to a lot of gassiness and bloating. There may also be sugar added to improve the flavor. Read your labels!

Methylcellulose is also a popular supplement, mainly because it is not fermentable. Thus, it does not cause much gas or bloating. Since it is 100% soluble, it will not help much with constipation or irritable bowel syndrome (IBS).

Calcium polycarbophil is a synthetic fiber. This gives it the advantage of not being fermented in the colon and not causing gas. Also, since it is 100% insoluble, it helps bulk up bowel movements. Thus, it is beneficial in constipation, diarrhea, and IBS. It comes in tablet or chewable forms. A bonus is that it contains a lot of calcium.

Another popular supplement that does not cause much gas is wheat dextrin. This is a 100% soluble fiber that is made from cooked wheat flour. It comes in a powder form. While beneficial for diabetes and cholesterol management, because it is soluble it has less effect on bowel function than other supplements. Of course, being made from wheat, it should be avoided by individuals with celiac disease or gluten intolerance.

Which Is the Best Supplement?

It all depends on why one is taking the supplement. If the issue is bowel regulation, an insoluble fiber such as calcium polycarbophil may be best. But watch the dose, you may need to take a lot of tablets to reach your fiber goal. If heart, diabetes, and metabolic considerations are paramount, consider a fully soluble product such as wheat dextrin. The best overall product is psyllium, because it contains a mixture of soluble and insoluble fibers. Build up the dose slowly, to reduce the problem from gas. Look for a product that contains both the seed and husk for the best mix. Remember with all fibers, drink a lot of liquid with them and never consume the powder without mixing it in water first.

The solubility, form, taste, and side effects of supplements vary. The best fiber is the one you actually take every day.

For more information, consult your doctor or a nutritionist.

Benjamin Krevsky, MD, MPH

Benjamin Krevsky, MD, MPH is a Professor of Medicine at Temple University School of Medicine. Dr. Krevsky is regularly listed as one of the Best Doctors in America and has been selected as a Top Doctor in Philadelphia Magazine. He is an active clinician and educator, having published over 200 papers, audiotapes and books. His clinical interests include colon cancer screening and treatment, anorectal disorders, motility disorders, and endoscopic treatment of gastrointestinal diseases. He has been honored with selection as a Fellow of the American College of Physicians, American Society for Gastrointestinal Endoscopy, American Gastroenterological Association, and American College of Gastroenterology. 

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