How to Spot ‘Fake’ Fiber in Your Foods

Most U.S. adults should add more fiber to their diet, but nutrition experts say it’s not enough to rely on fiber that’s added to processed foods.

Some dietitians on social media have called attention to “fake” fiber that appears on a packaging label, but doesn’t actually offer the same health benefits as fiber in whole foods like fruits and vegetables.

What Are ‘Fake’ Fibers?

Fake fiber isn’t a scientific term. It’s a popular phrase used to describe highly processed fibers that are added to foods, according to Debbie Petitpain, MBA, RDN, a Charleston-based registered dietitian and spokesperson for the Academy of Nutrition and Dietetics.

“They are sometimes called functional fibers, isolated fibers, or added fibers,” Petitpain told Verywell.

Fiber that naturally occurs in whole foods provides other nutrients like vitamins, minerals, plant compounds, and water, Petitpain said. However, “fake” or isolated fibers are extracted from plants or made in a lab and then added to foods to boost the fiber content on the nutrition label.

“Generally, they’re added to make processed foods seem healthier without changing the base ingredients, so a product can be marketed as ‘high fiber’ or ‘good source of fiber,'” Petitpain said.

Foods are considered “high fiber” if they contain at least 20% of the recommended Daily Value (28 grams) of fiber per serving.

How to Spot Fake Fibers on Nutrition Facts

To find fake fibers on a nutrition label, look for “dietary fiber” under the “total carbohydrates” heading.

If you see a surprisingly high amount of fiber—about 8-10 or more grams in a small serving of a food that lacks sources of natural fiber like whole grains, vegetables, or legumes—that’s a sign isolated fibers were added, according to Matthew Landry, PhD, RDN, an assistant professor of population health and disease prevention at UC Irvine.

The Food and Drug Administration (FDA) allows both natural and added fibers to count toward a processed food’s total dietary fiber. Since this number alone doesn’t signal if fibers are natural or added, it helps to check the ingredient list for additional clues.

Look for added ingredients like inulin, chicory root fiber, polydextrose, resistant maltodextrin, or soluble corn fiber, Landry added. Other added fibers to watch for include cellulose, rice bran, and xanthan gum.

Are Fake Fibers Harmful?

Adults need between 25 and 35 grams of dietary fiber per day to add bulk to stool and help lower blood sugar and cholesterol levels. While it’s best to get fiber from whole foods, the so-called fake fibers likely won’t hurt your health.

“Added fibers are not inherently harmful, but they’re not nutritionally equal to whole-food fiber. They can help close gaps for people who are falling a bit short,” Petitpain said.

As you increase your fiber intake, even if it’s from added fibers, drink plenty of water and give your gut time to adjust so you don’t have gas or bloating, she added.

The FDA has stated that some added fibers, specifically beta-glucan, psyllium husk, cellulose, guar gum, pectin, locust bean gum, and hydroxypropyl methylcellulose, may offer human health benefits. These fibers could help lower glucose and blood pressure, and promote regular bowel movements.