Before You Buy Fiber Supplements

What You Need To Know Before You Choose A Fiber Supplement

Psyllium Pills
Psyllium is one type of fiber that may be used to both firm up a stool or make it easier to pass.. Image © Roel Smart / E+ / Getty Images

Not all fiber supplements are created equally, so how do you know which one to choose? Fiber supplements may be prescribed for both diarrhea and constipation. If that seems strange, it won't after you understand how fiber works. Fiber will bulk up stool, making it firmer if it's too loose. It will also help if stool is too hard, by making it easier to pass. The goal is a good bowel movement that passes easily, without straining.

There are three main types of soluble fiber supplements: psyllium, methylcellulose, and polycarbophil. Each type of fiber has varying uses, side effects, and properties. Talk with your doctor about fiber supplements to decide which is best for your body. When shopping for fiber, look closely at the ingredients to discover which type of fiber is used in each commercial brand. Also be aware of additives in your fiber supplement, you probably don't need added sugars, flavorings, or colors. If you're just starting with a fiber supplement, use a low dose and and drink plenty of water when you take it.


Brand names: Metamucil, Fiberall, Hydrocil, Konsyl, Perdiem, Serutan

Psyllium is a fiber supplement that can be taken every day to bulk up stool, making it easier to pass. It works by breaking down in the gut and becoming a food source for the "good bacteria" that lives there. Psyllium is used for treating constipation, irritable bowel syndrome (IBS) and diverticulosis.

In addition, psyllium may also lower cholesterol levels by 10% to 15% in some people. On the downside, psyllium does contain calories and may cause intestinal gas.


Brand name: Citrucel

Methylcellulose is a fiber that is nonallergenic, non-fermentable, can be taken every day, and is created from the cell wall of plants.

It is not absorbed by the intestinal tract but instead absorbs water to create a softer stool. Methylcellulose is often used to treat constipation, diverticulosis, IBS, and some causes of diarrhea. Because it does not ferment, it is less likely to cause intestinal gas.


Brand names: Fibercon, Fiber-Lax, Equalactin, Mitrolan

Similar to methylcellulose, polycarbophil is created from plants and is not absorbed by the body. It absorbs water in the intestinal tract and creates a bulkier and softer stool. Polycarbophil is less likely to cause bloating and can be used long term. It may be used to treat constipation, IBS, and diverticulosis. This form of fiber is not appropriate for people who have difficulty swallowing.

Check With Your Doctor

All these forms of fiber are available over-the-counter, and are generally safe to use. However, if you're considering starting to take fiber every day to treat a medical condition, you should talk to your doctor first. You'll want to make sure that you're taking the type that will work best for you, and that you are taking enough.

In addition, if you are experiencing diarrhea or constipation on a regular basis, you may need to be evaluated for a digestive condition before you start treating the problem with fiber.


Natural Standard Research Collaboration. "Psyllium." MedlinePlus 26 Dec 2012. 7 Apr 2014.

Drug Digest. "Psyllium Capsules." Drug Digest 2 Apr 2014. 7 Apr 2014.

Continue Reading