For someone following a typical Western diet high in animal fat, animal protein, and sugar, it can be difficult to meet the minimum daily recommended value of dietary fiber (25g per day for women, and 38g per day for men).
What is fiber, and why is it so essential that you make dietary changes to increase your daily intake?
What is fiber?
With increasing research and discoveries, a precise definition of fiber can be tricky, but here’s what we do know:
Dietary (edible) fiber exists in the plant foods (fruits, vegetables, whole grains, beans/legumes, nuts, seeds) that we consume in the form of soluble and insoluble fibers
Soluble fibers dissolve in water and are essentially digested by the body
Insoluble fibers are not dissolvable in water and cannot be digested by the human body, however are essential to digestive function and effect many other functions in the human body
Generally speaking, the inside of an apple, for example, contains a soluble (digestible) fiber - pectin. The skin of the apple contains insoluble fibers that cannot be digested by the human body but they will aid in digestion processes.
What does fiber do for us?
While fiber does not provide the body with energy, it does provide many other benefits.
Improved Gut Microbiome
One of the most important functions that fiber does for us is to keep our gut balanced. Soluble fiber provides the main carbon and energy source for the gut microbiome and has prebiotic effects. Digestive tracts of individuals with a higher fiber intake have increased beneficial bacteria when compared to those who have a low fiber intake. There are thousands of different bacteria continuing to be studied in the gut microbiome. Two main bacteria of interest are bifidobacteria and lactobacilli as they have been found to be positively linked to improved health status when their count is higher in the gut.
Cereals are a primary source of β-glucagon, which have been linked to an increase of bifidobacteria and lactobacilli in the gut.
The pectin found in fruits like apples have been linked to an improved diversity in the gut-microbiome.
Weight Management
Fiber helps in weight management by providing bulk to food that helps keep you feeling full and satisfied for longer periods of time after a meal or snack. For this reason it also helps reduce overall intake, so it can be beneficial in reducing the over consumption that generally leads to weight gain.
Slows and Reduces Risk of Disease Processes
Higher fiber diets are beneficial to reducing the risk of various disease states like obesity, Type 2 Diabetes Mellitus, Hyperlipidemia, and Metabolic Disease. High levels of inflammation in the body are related to these disease states and many others. Fiber helps to down regulate proinflammatory cytokines (small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells) in the body, helping to reduce risk of illness.
Fiber also helps to reduce risk of cancer. Fiber plays an important role in killing off cancer cells (cancer cell apoptosis) in the colon, which can help prevent colon cancer.
Reduce Toxic Load
Fiber has binding properties with metal ions in the body that helps to rid the body of inorganic compounds that can lead to inflammation, infection, and illness. A diet low in fiber can be at risk of toxic overload, which can cause an array of symptoms depending upon the host and the type of metal overload.
How much fiber should I consume daily?
There are several factors at play in determining how much fiber you should consume in a day. The Academy of Nutrition and Dietetics recommends consuming 14g of fiber per 1,000 calories daily.
Fiber guidelines for Americans as per the Dietary Guidelines for Americans 2020 - 2025, based on 14g of fiber per 1,000 calories daily.
Age | Female | Male |
6-11m | N/A | N/A |
12-23m | 19g/day | 19g/day |
2-3y | 14g/day | 14g/day |
4-8y | 17g/day | 20g/day |
9-13y | 22g/day | 25g/day |
15-18y | 25g/day | 31g/day |
19-30y | 28g/day | 34g/day |
31-50y | 25 | 31 |
51+y | 22g/day | 28g/day |
Risks Associated with Fiber Intake
There are risks with a sudden increase in fiber intake:
Abdominal pain
Flatulence
Constipation
Diarrhea
While it is important to consume at a minimum the daily recommended amount of fiber, suddenly and drastically increasing your fiber intake could lead to discomfort. It is best to slowly introduce fiber into your diet one serving (or even half) and meal or snack at a time.
Resources
American Cancer Society. (2019, December 27). Cytokines and Their Side Effects.
ines.html#:~:text=Cytokines%20are%20small%20proteins%20that
Easy Ways to Boost Fiber in Your Daily Diet. (n.d.). Www.eatright.org. \
ber-in-your-daily-diet#:~:text=Fiber%20is%20an%20essential%20nutrient
fiber. (n.d.). Www.eatright.org.
Guan, Z. W., Yu, E. Z., & Feng, Q. (2021). Soluble Dietary Fiber, One of the Most Important
Nutrients for the Gut Microbiota. Molecules (Basel, Switzerland), 26(22), 6802.
Holscher H. D. (2017). Dietary fiber and prebiotics and the gastrointestinal microbiota. Gut
microbes, 8(2), 172–184. https://doi.org/10.1080/19490976.2017.1290756
United States Department of Agriculture. (2020). Dietary Guidelines for Americans 2020
Dietary_Guidelines_for_Americans_2020-2025.pdf
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