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Dietary Fiber and Chronic Disease: What’s the Connection?

The prevalence of chronic conditions of all kinds are continuing to rise across the globe, impacting the lives of many. Some examples of chronic diseases are diabetes, cancer, cardiovascular disease (CVD), gastrointestinal diseases, chronic obstructive pulmonary disease (COPD), and chronic kidney disease (CKD) [i]. The CDC reports that in 2018, “more than half (51.8%) of adults had at least 1 of 10 selected diagnosed chronic conditions…and 27.2% of US adults had multiple chronic conditions” [ii].

Fortunately, there are several ways that people can reduce their risk of chronic disease as many of the disease-contributing factors are modifiable lifestyle choices, such as diet. There may be certain foods or food groups that contribute to or reduce the risk of chronic disease development, so it can be useful to take a deeper look at diet. For example, the 2020-2025 Dietary Guidelines for Americans states that dietary fiber is “…one of several ‘dietary components of public health concern’ due to underconsumption” [iii]. Thus, it has been advised that individuals increase their daily consumption of dietary fiber to meet the recommendation of 21-38 grams per day of fiber [iv]. Recent research has highlighted dietary fiber’s various benefits, one of which is its impact on chronic disease risk. 

In general, dietary fiber is found in unrefined carbohydrates or plants that are edible but non-digestible, meaning that fiber particles travel through the gastrointestinal (GI) tract unabsorbed and exit the body through fecal excretion. Undigested fiber in the GI tract is left to be fermented by the bacteria that live within the large intestine; and the byproduct of this fermentation is short chain fatty acids (SCFAs). It is these SCFAs that are thought to be partially responsible for fiber’s role in promoting bowel movements, decreasing blood sugar levels, and decreasing blood cholesterol levels [v]. Although fiber is most often known for its constipation-relieving effects, it is also crucial in the prevention and management of nutrition-related chronic diseases. 

There are two types of fiber, soluble and insoluble, that are categorized based on the physiological effects fiber has on the body. For example, soluble fiber dissolves in water, forming a gel-like material in the GI tract. Soluble fiber helps to soften stool and bind with excess substances within the body such as cholesterol and estrogen. Unlike soluble fiber, insoluble fiber cannot dissolve in water and instead adds bulk to the stool. Insoluble fiber helps with increasing bowel movements and is responsible for increasing overall GI health [iii]. Therefore, the role that dietary fiber plays within the body may depend upon which type of fiber is consumed. Examples of each type can be found here.

Let’s take a look at some of the data that support fiber’s role in decreasing the risk of chronic disease.

  • Diabetes and CVD: As we know, dietary fiber is a key component in controlling blood sugar levels and lowering blood cholesterol, thus not surprisingly, it has been researched in connection to diabetes and cardiovascular disease. In a study conducted in 2020 by Partula et al., the consumption of different types of dietary fiber in relation to risk of general chronic disease, high total dietary fiber consumption of greater than 27.9 grams per day for men and more than 23.4 grams per day for women, soluble fiber intake of at least 8.73 grams per day for men and 7.17 grams per day for women, and insoluble fiber consumption of more than 19.6 grams per day for men and 16.6 grams per day for women, were all associated with a decreased risk of type 2 diabetes. Whereas, only soluble fiber intake was associated with decreased CVD risk. Additionally, this study found that soluble fiber and total dietary fiber, specifically from fruit sources, were associated with a decreased risk of general chronic disease and mortality [vi].
  • Chronic Obstructive Pulmonary Disease (COPD): The long-term effects of dietary fiber intake on COPD risk were studied in 2020 by Szmidt et al. with conclusive findings. This study showed that long-term high dietary fiber intake, defined as consuming more than 26.5 grams of fiber per day, decreased COPD risk by 30%, with fiber in cereal and fruit having the greatest effects [vii].
  • Chronic Kidney Disease (CKD): A 2018 study by Mirmiran et al. investigating the relationship between dietary fiber and CKD risk found that, “…for every 5 g/d increase in total fiber intake, the risk of incident of CKD decreased by 11%.” When looking at the sources of dietary fiber that were associated with decreased CKD risk, participants that consumed more than 4.6 grams of vegetable fiber per day and greater than 1.3 grams of legume fiber per day were 37% and 32% less likely to develop CKD, respectively [viii]. Across each of these studies, the findings were that dietary fiber intake is associated with a decreased risk of some chronic diseases. However, it should be noted that each study found that certain diseases responded better to specific types of fiber and fiber sources, which could be useful in disease prevention and management strategies.  

  • Cancer: In addition to fiber’s effect on blood sugar and cholesterol levels, its effect on bowel movement promotion is another mechanism of action associated with decreased risk for some chronic diseases. It is theorized that because dietary fiber intake can increase fecal excretion, waste and toxins are eliminated from the body along with the excess estrogen and cholesterol bound to the fiber. This mechanism of fiber may decrease the risk of certain chronic conditions such as colorectal cancer and breast cancer. In a 2022 study conducted by Qi et al., participants with the highest total dietary fiber intake had a 31.4% lower risk of all-cause mortality and a 39.4% reduced risk of cancer mortality compared to those with the lowest dietary fiber intake. More specifically, high total fiber intake of more than 28.12 grams of fiber per day was associated with a reduced risk for breast cancer; and high soluble fiber intake was associated with a decreased risk for colorectal cancer [v]. Thus, this study supports the conclusion that dietary fiber intake may decrease the risk of chronic disease and enhances the argument that specific types of fiber have different roles in disease pathology.     

Overall, soluble or insoluble dietary fiber has been shown to be inversely related to chronic disease risk. Therefore, it is important to promote dietary fiber and ways to increase its intake to the public. One way to increase fiber intake is to consume a variety of whole, plant-based foods. A diet that includes a variety of fruits and vegetables, whole grains, legumes, nuts, and seeds will guarantee adequate intake of soluble and insoluble fiber. Along with the benefits of fiber, these plant foods are packed with an abundance of vitamins, minerals, and antioxidants, which may have an additional beneficial impact on chronic disease risk. Meeting the recommendation stated in the very beginning of consuming, on average, 21-38 grams of fiber per day from the sources listed above can be a simple, yet effective way to help to reduce the risk of a variety of chronic conditions.    


[i] Centers for Disease Control and Prevention (2022, July 21). About chronic diseases. CDC.gov. https://www.cdc.gov/chronicdisease/about/index.htm  Accessed October 5, 2022. 

[ii] Boersma, P., Black, L.I., & Ward, B.W. (2020). Prevalence of multiple chronic conditions among US adults, 2018. Centers for Disease Control and  Prevention, 17http://dx.doi.org/10.5888/pcd17.200130external icon.

[iii] Academy of Nutrition and Dietetics (2022, January). Dietary Fiber. EatRightPro.org. https://www.eatrightpro.org/news-center/nutrition-trends/foods-and-supplements/functional-fiber Accessed October 5, 2022. 

[iv] Mayo Clinic (2021, January 6). Dietary fiber: essential for a healthy diet. MayoClinic.org. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983 Accessed October 5, 2022. 

[v] Qi J, Gao J, Zhang Y, Hou W, Han T, & Sun C (2022). The association of dietary fiber intake in three meals with all-cause and disease-specific mortality among adults: the U.S. National Health and Nutrition Examination Survey, 2003-2014. Nutrients, 14(12):2521. doi: 10.3390/nu14122521. PMID: 35745250; PMCID: PMC9228910. 

[vi] Partula, V., Deschasaux, M., Druesne-Pecollo, N., Latino-Martel, P., Desmetz, E., Chazelas, E., Kesse-Guyot, E., Julia, C., Fezeu, L.K., Galan, P., Hercberg, S., Mondot, S., Lantz, O., Quintana-Murci, L., Albert, M.L., Duffy, D., Consortium, T.M.I, Srour, B., & Touyier, M. (2020). Associations between consumption of dietary fibers and the risk of cardiovascular diseases, cancers, type 2 diabetes, and mortality in the prospective NutriNet-Sante cohort. American Journal of Clinical Nutrition, 112(1), 195-207. https://doi.org/10.1093/ajcn/nqaa063 

[vii] Szmidt, M.K., Kaluza, J., Harris, H.R., Linden, A., & Wolk, A. (2020). Long-term dietary fiber intake and risk of chronic obstructive pulmonary disease: a prospective cohort study of women. European Journal of Nutrition, 59(5), 1869-1879. https://doi.org/10.1007/s00394-019-02038-w 

[viii] Mirmiran, P., Yuzbashian, E., Asghari, G., Sarverzadeh, S., & Azizi, F. (2018). Dietary fibre intake in relation to the risk of incident chronic kidney disease. British Journal of Nutrition, 119(5), 479-485. doi:10.1017/S0007114517003671

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