Understanding The Fiber Gap: Why Aren’t We Getting Enough?

5 min read

Understanding The Fiber Gap: Why Aren’t We Getting Enough?

Posted Aug 17, 2023 Updated Feb 27, 2024

Fiber is an essential nutrient that we all should be getting more of in our diet—but here’s the problem: we just don’t. In the United States, adult women and men need between 25 to 38 grams of fiber daily. But on average, most Americans get 16 to 17 g of fiber daily.1 Recent research describes that fewer than 1 in 10 U.S. adults meet their daily recommendations for fiber intake.2

Are we doing any better across the globe? In Europe, a publication described that total fiber intakes are higher than in North America, with total intakes ranging from 15-25 g/day in adult men and 14-21 g/day in adult women. A little bit better! But collectively, we are still falling short.3

We struggle to get enough, and the question is…why?

Why Is There a Fiber Gap?

Food contains a matrix of nutrients and fiber is just one of them. Fiber occurs naturally in various fruits, vegetables, legumes, and whole grains. But you’ll also find isolated or synthetic fiber added to some foods, beverages, and supplement products. And not all fiber is the same, with key differences between soluble and insoluble fiber. Therefore, it might be difficult to identify what fiber(s) you are consuming from these various foods, and how much you’re consuming. In other words, a big reason for the fiber gap is that you might not know what foods contain fiber and if those foods are giving you enough fiber. 

And when it comes to “enough fiber”, many of us typically fall short simply because we need to consume a lot of high-fiber foods to meet our recommended fiber intake.4 Most foods don’t contain an abundance of fiber in a typical portion or serving. For example, a medium apple with skin only contains around 4g of fiber. That’s why it’s helpful to incorporate fiber at every meal and snack to ensure that you’re getting enough. It requires some planning to hit that 25 to 38 g/day recommendation!

How to Find Fiber and Fill the Fiber Gap

As a registered dietitian nutritionist (RDN), I often worry about the fiber gap in our diets because fiber is so crucial to our overall health. Modern-day diets are very different from our ancestors, which contained substantially more fiber due to the inclusion of various plant-based foods. Ancestral humans might have consumed as much as 100 g of fiber daily. That’s simply astonishing!

How can you add more fiber to your diet? Here are my tips to help you fill your fiber gap:

Meet With a Registered Dietitian Nutritionist (RDN)

First and foremost, it’s important to speak with a registered dietitian nutritionist (RDN) or a qualified healthcare provider to determine if you are getting enough fiber in your diet. They can help you devise a plan to incorporate fibrous foods that are also practical for you to fit into your daily routine.

Add More High-Fiber Foods

This tip might seem simple, but it’s the most effective way to fill the fiber gap. I suggest eating a variety of your favorite fruits, vegetables, whole grains, and legumes. In addition to their fiber content, these foods deliver essential vitamins and minerals without adding many calories.  

Here are some of my favorite high-fiber foods:

  • Lentils
  • Mushrooms
  • Artichokes
  • Plums
  • Wheat-based cereals

Incorporate a Variety of Fibers

Plant-based foods contain a diversity of fiber types—remember not all fibers are the same! For example, oats contain the soluble fiber type called Beta-glucan whereas asparagus contains inulin. You can support the diversity of the bacteria in your microbiome by eating a wide range of plants and benefiting from the different fibers they contain.

Dr. Joanne Slavin, Ph.D., RD says, “For most consumers, the best strategy to meet fiber recommendations is to find foods or beverages enriched with significant amounts of mixed fibers”. Incorporating a variety of fibers in your diet is key since different fibers have different effects on the body. 

Look at the Ingredients List

When purchasing packaged foods and beverages, look at the ingredient list and nutrition facts label to determine how much fiber one serving of that food or beverage provides and what sources of fiber you’re getting. 20% or more of the daily value for a nutrient such as fiber is high, so think about selecting products that contain a higher fiber load. On the ingredient list, look for key terms such as: 

  • Inulin
  • Chicory root
  • Oligofructose
  • Resistant starches or dextrins
  • Galactooligosaccharides
  • Fructooligosaccharides

The inclusion of one or a few of the above means that the product is formulated with fibrous ingredients. 

Start Slow to Allow Your Gut to Adjust

If you are a low-fiber consumer to begin with, then try adding fiber-rich foods gradually to allow your gut time to adapt to something new. Occasional bloating and flatulence may occur during this adaptation phase, but just know that this is completely normal and will subside with time. Be sure to drink more water and other fluids as you increase your fiber intake.

Fiber & The Fiber Gap: The Takeaway

Fiber plays a crucial role in our health and especially our digestive health. Fiber can provide nourishment for bacteria or microbiota that live within us. These bacteria stimulate beneficial metabolites called short-chain fatty acids that our body uses as an energy source for other cells.4 And this also helps support our immune system functioning.

In the U.S. and Europe, we still fall short of getting enough fiber in the diet. But proper meal planning and an eye for high-fiber food and drink sources can help close the fiber gap. So the next time you head to your kitchen for a meal or snack, think about what fibrous food sources you have on your plate or in your hand. And as a reminder, OLIPOP provides 9 grams of prebiotic fiber per serving. Now that’s a delicious way to help fill the fiber gap!


  1. National Center for Health Statistics. (2022, August 9). What We Eat in America, DHHS-USDA Dietary Survey Integration. U.S. Department of Health & Human Services. https://www.cdc.gov/nchs/nhanes/wweia.htm 
  2. Miketinas, D., Tucker, W. J., Douglas, C. C., & Patterson, M. (2023). Usual dietary fibre intake according to diabetes status in USA adults – NHANES 2013–2018. British Journal of Nutrition, 1–9. https://doi.org/10.1017/s0007114523000089 
  3. Stephen, A. M., Champ, M., Cloran, S., Fleith, M., Van Lieshout, L., Mejborn, H., & Burley, V. J. (2017). Dietary fibre in Europe: current state of knowledge on definitions, sources, recommendations, intakes and relationships to health. Nutrition Research Reviews, 30(2), 149–190. https://doi.org/10.1017/s095442241700004x 
  4. McKeown, N. M., Fahey, G. C., Slavin, J., & Van Der Kamp, J. (2022). Fibre intake for optimal health: how can healthcare professionals support people to reach dietary recommendations? BMJ, e054370. https://doi.org/10.1136/bmj-2020-054370 
Cheat Sheet
  • Fiber is an essential nutrient required in the diet, but most Americans continue to fall short with average intakes of 16-17 g daily in adult men and women.
  • Reasons for the fiber gap: understanding and identifying what foods contain fiber and how to tease this out from other nutrients in food. And understanding the number of foods/beverages required to hit daily fiber requirements.
  • Finding fiber and filling the gap is possible with proper meal planning. Choose fibrous foods that are feasible to incorporate into your diet and aim for variety. The diversity of fibrous foods is favorable for your gut
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