The science has spoken: Dietary fiber provides several benefits to the body, helping to support digestive health, regularity, and satiety. The catch? 94% of Americans are not meeting recommendations for fiber intake, a discrepancy largely attributed to low intakes of vegetables, fruits, and whole grains—food groups that more than 85% of American adults are under-consuming. (With these stats in mind, it may come as no surprise that dietary fiber is considered a “nutrient of public health concern” in the most recent Dietary Guidelines for Americans.)* (1, 2, 7)

To put it simply, the fiber consumption gap is real—and the first step to bridging it is getting informed, not only about fiber's health benefits (and why it’s important to consume enough), but also different sources of fiber, from whole foods to supplements. We’ll cover all that—and more—in this piece.

Fiber 101: What is fiber?

First, let’s talk about fiber itself—namely, what it is and what kinds exist. Dietary fiber refers to edible fiber that can be sourced from plant foods; specifically, it’s the indigestible part of plant material that passes through the digestive system mostly intact. (This differs from other food components like fat, protein, and non-fiber carbohydrates, which the body can break down and absorb.) Functional fiber, on the other hand, refers to fiber that is either extracted or isolated from whole foods, then added back to foods or sold as a supplement. (Like dietary fiber, functional fiber also has proven health benefits.). The combination of these fibers—dietary fiber and functional fiber—is referred to as total fiber. (3, 4)

What does fiber do?

Dietary fiber is often classified into two distinct categories: soluble fiber and insoluble fiber. Each serves different purposes in the body. Soluble fiber dissolves in water, forming a gel-like substance that slows the movement of food through the digestive system (and increases the bioavailability of some minerals). Insoluble fiber, as the name suggests, does not dissolve in water. “Insoluble fibers are neither broken down nor absorbed,” explains Dr. Mastaneh Sharafi, PhD, Ritual’s VP of Scientific Affairs and a registered dietitian. “Rather, they draw water as they pass through the digestive tract, resulting in an increased stool bulk.”* (1, 5, 6, 9)

According to Dr. Mastaneh, both types of fiber are beneficial in their own ways—and both can contribute to feelings of fullness. The takeaway? Rather than focusing on specific types, pivoting the goal to get enough fiber overall is a better approach. (Bonus: Most fiber-containing foods contain both soluble and insoluble fiber in differing amounts.)* (1, 5, 6, 9)

How much fiber is recommended?

The adequate intake (AI) for fiber is 14 grams per 1,000 kcal—a technical way of saying that the amount of fiber one should target depends on caloric recommendations (which vary based on age, life stage, and assigned sex at birth†). As a general rule, The Academy of Nutrition and Dietetics recommends that adult women aim to eat around 25 grams of fiber per day, while adult men aim for around 38 grams. (And according to the most recent National Health and Nutrition Examination Survey (NHANES) data, more than 90% of women and 95% of men between the ages of 19-50 are not hitting those daily fiber recommendations.)* (2, 3, 7, 8)

Eating a high-fiber diet comes with a host of pluses—among them satiety support, digestive support, and gut support. Fiber may also support digestive health (helping with relief of mild and occasional constipation), not to mention many fibrous whole foods contain prebiotic fiber, which promotes the growth of beneficial gut bacteria. Diets higher in dietary fiber can help support heart health, too.* (1, 3)

Where is fiber found?

Dietary fiber is found in plant foods—which include fruit, veggies, beans, peas, lentils, seeds (including flax seeds, which also have omega-3 fatty acids), ready-to-eat high-fiber breakfast cereals, oats, popcorn, bran, and other whole grains. Much like micronutrients (aka vitamins and minerals), the best way to meet macronutrient needs is through food first. Dr. Mastaneh recommends striving for a balanced diet rich in whole foods—veggies, fruits, nuts, whole grains, legumes—and incorporating a fiber supplement if and when extra support is needed.* (10, 11)

Sources of soluble fiber include: (9)

• Peas
• Oats
• Beans
• Guar gum seeds
• Most fruits

Sources of insoluble fiber include: (9)

• Wheat bran
• Brown rice
• Most vegetables

Nothing strike your fancy? Here's some more high-fiber foods to explore—which brings us to…

Fiber supplements: What's the deal?

Whether someone struggles with tolerating high-fiber foods, has difficulties meeting intake levels, or simply wants to consume more fiber, a supplement can be a helpful tool to keep in a wellness arsenal.

There are many kinds of fiber supplements out there that range in form (such as caplets, fiber powders, and gummies) and type (including guar gum fiber, psyllium husk/psyllium fiber, inulin, and wheat dextrin), so it’s important to do the research and discern what you’re looking for when shopping. Do you want a gluten-free or sugar-free option? What form are you most likely to enjoy? How about sourcing methods and sustainability? Ultimately, the best fiber supplements are the ones you like and trust (and therefore, take)—so doing your due diligence on the front end will go a long way toward creating a lasting habit.*

Oh, and one more thing: If someone doesn’t currently eat a fiber-rich diet, drastically increasing it may cause temporary side effects, like bloating and/or gas—so we suggest starting slow, monitoring the body, staying hydrated, and as always, checking in with a trusted health care provider before making any sudden changes.* (9)

References

1. U.S. Department of Health and Human Services, Food and Drug Administration (FDA). Interactive Nutrition Facts Label. Dietary Fiber Fact Sheet. March 2020.
2. U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020.
3. Institute of Medicine of The National Academies. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). 2005, 7:399-400.
4. Mayo Clinic. Nutrition and Healthy Eating. Dietary fiber: Essential for a healthy diet. Last updated Jan. 6, 2021. Accessed June 22, 2021.
5. Chutkan, R.; et al. Viscous versus nonviscous soluble fiber supplements.... J Am Acad Nurse Pract. 2012, 24(8):476-87. (Abstract)
6. Dahl, W. J., & Stewart, M. L. (2015). Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber. Journal of the Academy of Nutrition and Dietetics, 115(11), 1861–1870.
7. USDA, Agricultural Research Service, 2021. Usual Nutrient Intake from Food and Beverages, by Gender and Age, What We Eat in America, NHANES 2015-2018. 2021.
8. Institute of Medicine. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Washington, DC: The National Academies Press; 2006.
9. U.S. Department of Health and Human Services, National Institutes of Health (NIH). News in Health. Rough up your diet. August 2019.
10. U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2020-2025 Dietary Guidelines and Online Materials. Food Sources of Dietary Fiber. 2020.
11. Rodriguez-Leyva, D., Dupasquier, C. M., McCullough, R., & Pierce, G. N. (2010). The cardiovascular ...flaxseed and its omega-3 fatty acid, alpha-linolenic acid. The Canadian journal of cardiology, 26(9), 489–496.
12. USDA. (n.d.). Macronutrients. National Agricultural Library.