DIETITIANS LIKE ME have been recommending a fiber-rich diet for years. The average American consumes between 10 to 15 grams of fiber in their diet daily. (The recommendation is between 20 to 38 grams, depending on age and gender). A big part of the problem is that only one in 10 of us eat enough fruits and vegetables, which are high in fiber.
But now many food manufacturers are pumping fiber into things most of us love—soda, chocolate peanut butter protein bars, boxed mac ‘n’ cheese.
Maybe you’ve even been shocked (as I have) by extreme examples of this. Like a single high-fiber tortilla that packs a wild 16 grams of fiber—roughly half of the recommended daily intake for most people.
And you probably have questions.
- How can foods and drinks that don’t typically have a lot of fiber have a lot of fiber?
- Is this added fiber in packaged foods equal to the fiber from whole foods?
- Can you eat two high-fiber tortillas and be done with your fiber intake for the day?
I have answers.
Why Does Fiber Matter Anyway?
The benefits of getting adequate fiber for most people can’t be understated: weight maintainence, cardiac health, intestinal regularity (yes, that means good poops), better gut health, glucose control, lower cholesterol.
And, until recently, fiber was really only found in whole foods—grains, fruits, vegetables, beans, legumes, etc.—which each have loads of other healthful nutrients.
Where Does the Fiber in Packaged Food Come From?
It’s called functional fiber.
Functional fiber is a type of fiber that has been added to packaged food to increase fiber content. It’s not the same as dietary fiber, which occurs naturally in food. While it’s true that many types of functional fiber are also found in whole foods, functional fibers are often used in larger amounts in packaged foods.
Most fiber-enriched products use functional fibers like inulin, polydextrose, modified wheat starch, and psyllium to bump up their fiber content. While these ingredients aren’t harmful in moderate amounts, and they can be beneficial to health, there are a few good reasons why functional fibers aren’t meant to be the sole source of fiber in your diet.
Is Functional Fiber Good for You?
Well, how much are you eating?
As a society, we tend to believe that more is better when it comes to the good stuff, but nutrition doesn’t really work like that. In the case of functional fiber, consuming large amounts of it can cause some serious issues for some people.
For example, some prebiotic sodas use inulin as their fiber. Inulin is a fermentable carbohydrate which our good gut bugs feed on (that’s a good thing), but that can cause gastrointestinal distress such as gas and bloating in some people (not good).
Ultra-processed foods that contain functional fiber often lack the other benefits of naturally fiber-rich foods such as fruits, vegetables, nuts, seeds, and whole grains.
The fiber in these whole foods is typically packaged with antioxidants, vitamins and minerals, water, and unlike fiber-enriched packaged foods, a mix of different fiber types. Getting a mix of fibers in your diet is important, because each type of fiber has different characteristics and effects on the body. Some, like inulin, are fermented rapidly and feed the microbiome. Psyllium undergoes minimal fermentation, but is still beneficial for adding stool bulk. (Fun!)
If you’re sensitive to fermentable carbohydrates (FODMAPs), functional fibers can trigger symptoms. Everyone’s tolerance is different, but it’s not advisable to consume the entirety of your fiber in functional form.
It’s also important to note that even dietary fiber in large amounts can cause issues for some individuals. People with IBS, IBD, and other digestive conditions and diseases may need to avoid a high-fiber diet, regardless of the source.
Consuming too much fiber—generally over 40 grams a day—can interfere with mineral absorption, in particular calcium, iron, and zinc. In rare cases, the overconsumption of fiber can lead to intestinal blockage. Yes, not fun.
To prevent constipation, always make sure that you consume adequate fluids, especially when you’re ramping up your fiber intake.
The Bottom Line
The best way to consume fiber is through a variety of whole foods. If you enjoy (and tolerate) fiber-enriched products, use them as a “top-up” for your fiber intake, rather than making them your main source. Instead of focusing on fiber grams, try to focus on adding more whole, naturally fiber-rich foods into your diet.
Ultra-processed foods are still ultra-processed, and the addition of fiber doesn’t put them on equal nutritional ground as whole foods.
Abby Langer, RD is the owner of Abby Langer Nutrition, a Toronto-based nutrition consulting and communications company
