Most of us are well aware of the health benefits of dietary fiber. You don't even need to be a dietitian these days to know that fiber boosts digestive health and can help reduce risk of heart disease.
Still, apparantly only about 5% of Americans are meeting their daily fiber needs. Wow, that is low!
Inadequate fiber can contribute to poor digestive health (constipation, hemorrhoids, diverticular disease), higher cholesterol panels, poor health of the gut bacteria, poor blood sugar control, and even weight gain. A high fiber diet is also linked to reduced risk of colon cancer.
What is fiber?
Fiber is a type of carbohydrate from plant foods that the body cannot digest or absorb. We find it in beans, peas, fruits, nuts, seeds, vegetables, bran, and whole grains.
It passes through the gastrointestinal system mostly intact. Some fibers may be broken down to some degree by bacteria residing in the colon.
The two main types of fiber are insoluble and soluble fiber.
- Insoluble fiber is the roughage that passes almost entirely intact through the GI system. (Think apple or potato skins!)
- Soluble fiber dissolves in water, forming a thick gel-like substance in the stomach. It can be broken down by bacteria in the colon. (Think of what happens when you mix chia seeds with water!)
These two types of fibers are what we call naturally ocurring fibers or intrinsic fibers because they are naturally found in plant foods, not added to them.
Understanding Fiber Information on Labels
When you look up the total amount of dietary fiber in a product, however, it will not solely reflect the amount of naturally ocurring fibers in the food. Some products have synthetic, or isolated fibers in them. These are fibers extracted from plants or foods and added to foods or supplements to boost their fiber content or health benefits.
The total dietary fiber amount on your label can reflect the amount of these fibers, too, if they are on the list of FDA-approved synthetic fibers.
These are:
• beta-glucan soluble fiber
• psyllium husk
• cellulose
• guar gum
• pectin
• locust bean gum
• hydroxypropylmethylcellulose
Additionally, the FDA plans to also approve these fibers and count them toward the total dietary fiber in a product:
• mixed plant cell wall fibers (a broad category that includes fibers like sugar cane fiber and apple fiber, among many others)
• arabinoxylan
• alginate
• inulin and inulin-type fructans
• high-amylose starch (resistant starch 2)
• galactooligosaccharide
• polydextrose
• resistant maltodextrin/dextrin
• cross-linked phosphorylated RS4
• glucomannan
Again, the only reason the FDA adds these synthetic fibers to the TOTAL dietary fiber number is because they have been evaluated for adequate scienfitic proof of their health benefits.
Bottom line: Dietary Fiber = Fiber naturally occurring in plants + added synthetic fiber that has a proven health benefit for humans.
Other Fibers
Ingredient lists might have some other hard-to-pronounce fibers listed. These include:
- carboxymethylcellulose
- gum acacia
- karaya gum
- pullulan
- retrograded corn starch (RS3)
- xanthan gum
-xylooligosaccharides
Yes, these are fibers. However, they aren't counted towards your TOTAL DIETARY FIBER number on the label because they are non-beneficial and non-digestible. This is a protection from deceiving product labeling about fiber claims.
More on that Fiber Gap ...
If you look up fiber recommendations, the USDA will tell you for those younger than 50,
- men need 35 grams daily
- women need 25 grams daily
and for those older than 50,
- men need 30 grams daily
-women need 21 grams daily.
Research, however, is showing that we can benefit from even more than these recommendations. Yet, most are struggling with the bare minimum. What are some simple ways to boost your fiber intake?
- Keep cut-up veggies on hand for quick snacks
- Add fruit to salads and side dishes
- Try whole grains
- Add beans to salads, soups, and side dishes
- Snack on unsalted nuts and seeds
References
Quagliani D, Felt-Gunderson P. Closing America’s fiber intake gap: communication strategies from a food and fiber summit. Am J Lifestyle Med. 2017;11(1):80-85.
Kunzmann, A. T., Coleman, H. G., Huang, W. Y., Kitahara, C. M., Cantwell, M. M., & Berndt, S. I. (2015). Dietary fiber intake and risk of colorectal cancer and incident and recurrent adenoma in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. The American journal of clinical nutrition, 102(4), 881–890. https://doi.org/10.3945/ajcn.115.113282
Questions and answers on dietary fiber. U.S. Food and Drug Administration website. https://www.fda.gov/food/food-labeling-nutrition/questions-and-answers-dietary-fiber. Updated January 30, 2020. Accessed November 30, 2020.
Lancet. 2019;393(10170):434-445.