By Roberta H. Anding, MS, Baylor College of Medicine and Texas Children’s Hospital

Edited by Kate Findley, The Great Courses Daily

Many people turn to fiber supplements such as Metamucil^® to find relief from constipation. However, there are more effective options, as Professor Anding explains.

Insoluble Fiber and Constipation

Lately, fiber has been portrayed in health news as an antidote to constipation, and while this has some truth, this benefit largely depends on the type of fiber that’s predominant. Insoluble fiber has the primary role of regulating bowel function, especially the movement of food through the intestines. 

When we consider all the products currently on the market that are supposed to be natural colon cleansers, keep in mind that insoluble fiber is nature’s way of regulating bowel function. Thus, you don’t necessarily need to step over into the supplement world, as most supplements primarily contain soluble fiber.

Insoluble fiber increases the size of the stool, helping to eliminate constipation. Sources include whole grain breads and cereals, nuts, vegetables, green beans, and celery.

Should You Use Supplements?

In cases of severe or chronic constipation, fiber supplements may sometimes be necessary. In most cases, though, supplements may provide a quick fix but don’t help the issue in the long-term.

“I want to caution you here that if you have an individual in your family who suffers from constipation, and you really do need to go to a fiber supplement, keep in mind it is the insoluble fiber that promotes optimal bowel functioning,” Professor Anding said. “If you’re going to provide a fiber supplement, why not try something like unprocessed wheat bran?” 

You can buy unprocessed wheat bran in most health food stores, and it’s usually around 50 cents a pound. It mixes in many different kinds of food. 

For example, you can mix wheat bran in mashed potatoes, yogurt, or applesauce. According to Professor Anding, it is a highly effective treatment for constipation. By contrast, most of the fiber supplements on the market are not insoluble fiber—the best regulator of optimal bowel health—but soluble fiber.

What Is Soluble Fiber?

Soluble fiber forms a gel when it’s dissolved in water. Foods that contain primarily water-soluble fiber include pears, apples, many citrus fruits, berries, and carrots. 

Soluble fiber can help to lower cholesterol and control blood sugar or blood glucose levels. Sources of insoluble fiber are typically gummy, but sometimes you can’t tell because these predominantly water-soluble fibers may contain an insoluble coating.

Oatmeal is one example, along with peas, where the inside is predominantly a gummy or gel fiber, but it’s protected from its gumming or gelling function by the hard outer coating. Additionally, red beans and pinto beans have a fibrous coating, but when they break open in the water, they release a water-soluble fiber. Overall, not one food is exclusively soluble or insoluble fiber. 

When it comes to dietary supplements, psyllium—which is 70% soluble fiber and made from the husks of the Plantago ovata plant’s seeds—is found in many of the high-fiber breakfast cereals. If you look at the nutrition facts panel on the back of the cereal box, you can search for psyllium fiber. It’s also the fiber that’s found in the supplement Metamucil. 

Many commercial products designed for the treatment of constipation are based from psyllium. However, it’s already been established that the other type of fiber—water-insoluble fiber—is best for the treatment of constipation. Thus, Professor Anding recommends turning to sources of insoluble fiber such as wheat bran rather than supplements for bowel regularity.

This article was edited by Kate Findley, Writer for The Great Courses Daily.

Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.