A Deep Dive into Dietary Fiber and Disease Prevention

Dietary Fiber and Disease Risk

Dietary fibers are carbohydrates that our bodies cannot digest―they are what is left over after we digest and absorb proteins, fats, starches, and sugars. When we eat foods containing dietary fiber, the undigested fiber moves through the stomach and small intestine to the colon (large intestine). Once in the colon, fiber works in a variety of ways to promote better health.

Dietary Fiber and Disease Prevention

While humans cannot digest dietary fiber, the bacteria found in our colons are able to break down dietary fiber in a process called “fermentation.” Fermentation of fiber supports the growth of a healthy balance of good bacteria in the colon. Additionally, the process of fermentation produces substances that promote the health of the colon and the body as a whole.

Which chronic diseases might dietary fiber help to prevent?

Consuming a diet higher in dietary fiber is linked to a decreased risk of developing cardiovascular (heart) disease, type 2 diabetes, bowel disease, and chronic kidney disease. For every additional 5 g of fiber per day you decrease the risk of developing chronic kidney disease by more than 10%. Higher dietary fiber intakes are also linked to overall survival. Each additional 10 g of fiber per day reduces the risk of death by 10%. Higher intakes of dietary fiber are also related to lower body weight.

How does dietary fiber help those with an existing chronic disease?

Diets high in dietary fiber promote better health in a number of ways. A higher dietary fiber intake will help to bulk the stool and promote regularity. Some dietary fibers, such as those found in oatmeal and legumes, can help to reduce total blood cholesterol and LDL (bad) cholesterol; lower LDL cholesterol helps to reduce the risk of heart disease. Dietary fiber may also help reduce blood glucose and blood insulin levels, which is helpful for the prevention and management of type 2 diabetes. Fermentation of dietary fiber produces substances known as “short-chain fatty acids” that may help reduce inflammation that contributes to most chronic diseases. This reduced inflammation related to consuming dietary fiber is thought to be especially important for those with chronic kidney disease.

How can I increase my dietary fiber intake?

There are many ways to increase dietary fiber intake. Here are a few simple tips:

• Choose whole-grain breads, cereals, and pastas instead of refined grain foods.
• Double your serving of vegetables at lunch and dinner.
• When snacking, choose whole fruits, nuts, and seeds.
• Dietary fiber intake can also be increased by choosing foods with added fiber, such as breakfast cereals and bread with added bran or hull fibers (e.g. wheat bran, oat bran, pea hull, and oat hull).

Summary

Dietary fiber is helpful in the prevention and management of many chronic diseases. Choosing foods like whole grains, legumes, fruits, vegetables, nuts, and seeds is a great way to increase dietary fiber intake.

References

1. Dahl, W. J., and M. L. Stewart. 2015. “Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber.” J Acad Nutr Diet. 115(11): 1861‒70. doi: 10.1016/j.jand.2015.09.003.
2. Dahl, Wendy J., Nicole C. Agro, Åsa M. Eliasson, Kaley L. Mialki, Joseph D. Olivera, Carley T. Rusch, and Carly N. Young. 2017. “Health Benefits of Fiber Fermentation.” Journal of the American College of Nutrition. 1-10. doi: 10.1080/07315724.2016.1188737.
3. Krishnamurthy, V. M., G. Wei, B. C. Baird, M. Murtaugh, M. B. Chonchol, K. L. Raphael, T. Greene, and S. Beddhu. 2012. “High dietary fiber intake is associated with decreased inflammation and all-cause mortality in patients with chronic kidney disease.” Kidney Int. 81(3): 300‒6. doi: 10.1038/ki.2011.355.
4. Liu, X., Y. Wu, F. Li, and D. Zhang. 2015. “Dietary fiber intake reduces risk of inflammatory bowel disease: result from a meta-analysis.” Nutr Res. 35(9): 753‒8. doi: 10.1016/j.nutres.2015.05.021.
5. Shay, C. M., L. Van Horn, J. Stamler, A. R. Dyer, I. J. Brown, Q. Chan, K. Miura, L. Zhao, N. Okuda, M. L. Daviglus, and P. Elliott. 2012. “Food and nutrient intakes and their associations with lower BMI in middle-aged US adults: the International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP).” Am J Clin Nutr. 96(3): 483‒91. doi: 10.3945/ajcn.111.025056.
6. Threapleton, D. E., D. C. Greenwood, C. E. Evans, C. L. Cleghorn, C. Nykjaer, C. Woodhead, J. E. Cade, C. P. Gale, and V. J. Burley. 2013. “Dietary fibre intake and risk of cardiovascular disease: systematic review and meta-analysis.” BMJ. 347: f6879. doi: 10.1136/bmj.f6879.
7. Xu, H., X. Huang, U. Riserus, V. M. Krishnamurthy, T. Cederholm, J. Arnlov, B. Lindholm, P. Sjogren, and J. J. Carrero. 2014. “Dietary fiber, kidney function, inflammation, and mortality risk.” Clin J Am Soc Nephrol. 9(12): 2104‒10. doi: 10.2215/cjn.02260314.
8. Yang, Y., L. G. Zhao, Q. J. Wu, X. Ma, and Y. B. Xiang. 2015. “Association between dietary fiber and lower risk of all-cause mortality: a meta-analysis of cohort studies.” Am J Epidemiol. 181(2): 83‒91. doi: 10.1093/aje/kwu257.