Nutrition

Fiber 101: Food Sources, Supplementation, and More

5 min read

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Let’s start with some facts about fiber. First, it’s an important part of a healthy eating pattern, along with carbs, fat, and protein (not to mention water). Second, it happens to be one of the most overlooked components of a healthy diet; according to the most recent National Health and Nutrition Examination Survey (NHANES), more than 90% of women and 95% of men ages 19-50 in the United States are not consuming enough fiber from their diets. Third? Fiber comes with a host of health benefits, from supporting satiety and digestive health to regularity—so it just might be time to change that.* (1)

When it comes to building healthy new habits, knowledge is truly your friend: Taking the time to educate yourself on the foundations of fiber—understanding what it is, what it does, and how it supports the body—will enable you to understand the “why” behind what you’re doing, allowing you to make empowered decisions over the long-term. In this piece, we answer common fiber-related queries—covering everything from the different types of fiber and how they function in the body to high-fiber foods (and more). Let’s get into it.

Q: What is fiber?

Great question. To get really granular with it, fibers are non-starch carbohydrates and lignins that cannot be absorbed by the human stomach and/or intestinal enzymes—basically, a scientific way of saying that fiber refers to a type of carb that the body is unable to digest. (2)

Dietary fiber—the subject of this piece—specifically refers to edible fiber that can be found naturally in plant foods. Also known as roughage or bulk, it comes from parts of plant foods that our bodies are unable to absorb; this means that fiber passes through the digestive tract and out of the body (via bowel movements) fairly intact. (2, 3)

Q: What are the different types of fiber?

There are two types of dietary fiber: soluble fiber and insoluble fiber. “Both types are beneficial in their own ways,” says Dr. Mastaneh Sharafi, PhD, Ritual’s VP of Scientific Affairs and a registered dietitian. A quick crash course: Soluble fiber dissolves in water, forming a gel-like material that slows the movement of food through the digestive tract (while supporting the bioavailability of certain minerals). In contrast, insoluble fiber does not dissolve in water—it actually draws water into the digestive tract, promoting an increased stool bulk and encouraging the movement of food through the digestive system. (3, 4, 5)

Q: What are the benefits of fiber?

The importance of dietary fiber really can’t be understated. In addition to supporting digestive health, high-fiber diets—or, at the very least, diets high in fiber content—can help support heart health and ease mild and occasional constipation. Additionally, dietary fiber can contribute to feelings of fullness, supporting satiety. Most fiber-containing foods contain both soluble and insoluble fibers in differing amounts, so eating a well-varied, produce- and whole grain-rich diet is a solid approach to boosting overall fiber intake.* (4, 6)

Q: How much fiber is recommended?

Fun (not-so-fun?) fact: The fiber consumption gap in America is so acute that dietary fiber is actually considered a “nutrient of public health concern.” So, what is the recommended daily amount—in fiber’s case, referred to as the adequate intake (AI)? According to the Academy of Nutrition and Dietetics, the AI for fiber is 14 grams per 1,000 kcal, which translates to around 25 grams for adult women and 38 grams for adult men—though the exact amount of fiber recommended varies based on caloric needs.† (4, 5)

Q: What are some sources of fiber?

Fiber is predominantly found in fruits, vegetables, and whole grains—three food groups that more than 85% of Americans come up short against. More specifically, fiber is found in plant foods, which, in addition to fruits and veggies, also include legumes (kidney beans, black beans, peas, lentils), seeds (chia seeds, flax seeds), oats (including oat bran), popcorn, and other whole grains (whole-grain bread, whole-wheat bread, wheat bran, brown rice, bulgur). For context, fiber is typically not found in animal-derived protein foods like beef, pork, poultry, eggs, and seafood, or in dairy products like milk, yogurt, and cheese. (7, 8)

Q: What’s the deal with fiber supplements?

In general, we recommend following a food-first approach to nutrition—aiming to fulfill nutrient needs through a balanced, healthy approach to eating, then supplementing then rest. (This is true for both micronutrients and macronutrients.) The good news is that making a habit of incorporating fiber-rich foods doesn’t have to be difficult—check out this list for some easy (and tasty!) hacks.

Another option to up intake: Fiber supplements. They can be a helpful addition to any routine, especially if struggling with consuming or enjoying fibrous foods—or just want a time-saving way to support digestive health, regularity, and satiety. Studies show that fiber supplements can help boost fiber consumption and contribute to reaching recommended guidance levels while providing many of the same benefits as their food counterparts.* (9)

Just remember that when introducing changes to your diet—food-wise or supplement-wise—going slow and listening to your body is paramount. Suddenly and drastically increasing fiber intake may cause temporary side effects like bloating—so be sure to ease in gradually, monitor how you feel, and reach out to a healthcare provider with any questions.* (10)

References

  1. 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.
  2. 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.
  3. Chutkan, R.; et al. Viscous versus nonviscous soluble fiber supplements: Mechanisms and evidence for fiber-specific health benefits. J Am Acad Nurse Pract. 2012, 24(8):476-87. (Abstract)
  4. U.S. Department of Health and Human Services, Food and Drug Administration (FDA). Interactive Nutrition Facts Label. Dietary Fiber Fact Sheet. March 2020.
  5. 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.
  6. U.S. Department of Health and Human Services, National Institutes of Health (NIH). News in Health. Rough up your diet. August 2019.
  7. U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020.
  8. 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.
  9. James W Anderson, Pat Baird, Richard H Davis, Jr, Stefanie Ferreri, Mary Knudtson, Ashraf Koraym, Valerie Waters, Christine L Williams, ...dietary fiber, Nutrition Reviews, Volume 67, Issue 4, 1 April 2009, Pages 188–205.
  10. Zhang, M., Juraschek, S. P., Appel, L. J., Pasricha, P. J., Miller, E. R., 3rd, & Mueller, N. T. (2020). Effects of High-Fiber Diets and Macronutrient Substitution...Findings From the OmniHeart Trial. Clinical and translational gastroenterology, 11(1), e00122.

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Meet Our Experts

This article features advice and has been reviewed by members of our Science Team.

Science Thumb — Mastaneh

Dr. Mastaneh Sharafi, PhD, RD, VP of Scientific Affairs

Dr. Mastaneh Sharafi has a PhD in Nutritional Sciences and is a Registered Dietitian. She received her training from Penn State University and University of Connecticut where she researched dietary patterns, chemosensory perception and community nutrition. Her dietetic work is focused on promoting healthy eating habits by translating the science of nutrition into practical information for the public.

Science Thumb — Mastaneh

Dr. Mastaneh Sharafi, PhD, RD, VP of Scientific Affairs

Dr. Mastaneh Sharafi has a PhD in Nutritional Sciences and is a Registered Dietitian. She received her training from Penn State University and University of Connecticut where she researched dietary patterns, chemosensory perception and community nutrition. Her dietetic work is focused on promoting healthy eating habits by translating the science of nutrition into practical information for the public.

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