Nutritionist Tip: Benefits of Fiber
Updated: Sep 8, 2021
You’ve probably heard it over and again that fiber is good for you and you should include more fiber in your diet!
But what is fiber?
Fiber is essentially a carbohydrate. It’s made up of chains of glucose (sugar) connected in a particular way that cannot be digested nor absorbed by the human gut or enzymes. Fiber serves as a structural component of plants, similar to the bones we have in our bodies. So then why eat something that you cannot digest?
Even though we do not digest and absorb fibers, they still offer many health benefits. Fibers help to bulk up foods to increase their volume and help with the feeling of fullness, referred to as satiety and also slows digestion to keep you feeling full longer (2). Diets rich in fiber have also proven to help manage cholesterol, improve insulin sensitivity and decrease risk of colorectal cancers (1). While we don’t digest fibers, research has shown a fiber rich diet helps to promote activity and growth of healthy gut microflora, whereby serving as a prebiotic. Having healthy gut microflora helps protect the digestive tract from acute inflammation and has even been shown to benefit those with Inflammatory Bowel Disease (IBD), such as Crohn’s or ulcerative colitis.
For those struggling with high cholesterol and high blood sugar, fiber has been shown to improve low-density lipid (LDL) levels and moderate insulin response. The exact mechanisms by which LDL is reduced is not exactly known, but it is suggested that fiber binds to bile acids in the intestine. Bile acids are made from phospholipids and cholesterol by the gallbladder and liver and released when fats (lipids) are present in the small intestine for digestion. So, when fiber binds to released bile acids during digestions of fats, it increases the demand for bile acid production by the gallbladder and liver by using up more cholesterol and phospholipid reserves (1). Similarly, fiber also acts as a barrier to digestion of carbohydrates or starch in particular, resulting in a slower and more controlled release of insulin. Based on this process, research has revealed diets rich in fiber result in smaller waist lines (2). And for most that is the bottom line.
Based on surveys, the average American consumes around 10-15 grams of fiber daily. But based on USDA health recommendations, the daily intake of fiber for men should contain around 30-34 grams per day and for women should contain about 22-28 grams of fiber per day (1, 3). So, what does that mean for you? How can you increase your daily fiber intake? The best approach to increase your fiber intake is to increase your intake of whole and unprocessed foods. Foods like nuts, seeds, whole grains, rice, oats, beans, lentils, fruits and vegetables are all excellent sources of a variety of fibers to support healthy functions.
Aida Sadeghi, MS, CNS
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1 Chawla, R. and Patil, G. R. (Feb 16, 2010). Soluble Dietary Fiber. Comprehensive Reviews in Food Science and Food Safety, 9 (2), pp. 178-196. https://doi-
2 Du, H.; van der A, D.; Boshuizen, H.; Foroughi, N.; Wareham, N.; Halkjaer, J.; …; Feskens, E. (Dec 16, 2009). Dietary Fiber and Subsequent Changes in Body Weight and Waist Circumference in European Men and Women. The American Journal of Clinical Nutrition, 91 (2), PP. 329-336. https://doi.org/10.3945/ajcn.2009.28191.
3 Appendix 7: Nutritional Goals for Age-Sex Groups Based on Dietary Reference Intakes and Dietary Guidelines Recommendations. Dietary Guidelines 2015-2020. Retrieved from:
4 Zhang, C.; Ho, S.; Cheng, S.; Chen, Y.; Fu, J. et al. (Aug 2011). Effect of Dietary Fiber Intake on Breast Cancer Risk According to Estrogen and Progesterone Receptor Status. European Journal of Clinical Nutrition, 65 (8), pp. 929-936. DOI:10.1038/ejcn.2011.57.