You’ve probably heard about the importance of fiber in your diet. But if you’re like most North Americans, you’re not getting nearly as much as you should. (7)
That’s because the typical Western diet is high in sugar and fat (particularly animal fat), and generally low in sources of fiber such as fruit and vegetables. (19) When hunger strikes, we often grab food that’s fast and easy, rather than what our bodies need. Unfortunately, many of the convenient foods prevalent in typical North American diets lack the fiber our body needs.
But the good news is that it’s quite easy to increase your fiber intake. In this article, we’ll talk about the role of dietary fiber and its important health benefits, as well as how to get more fiber in your diet.
What is fiber?
Dietary fiber, sometimes referred to as roughage or bulk, is a type of carbohydrate present in plant foods that is resistant to digestion and absorption in the small intestine. Instead, it travels to the large intestine to undergo partial or full fermentation, after which it is excreted in your stool. (5)
Types of fiber
There are two types of fiber: soluble fiber and insoluble fiber. You may wonder which type of fiber is better for you, but the truth is that each type of fiber has an important role to play in maintaining good health.
1. Soluble fiber
Soluble fiber is the type of fiber that can dissolve in water, forming a gel-like consistency. You’ll find soluble fiber in legumes, oats, peas, nuts, seeds, psyllium husk, and certain fruit and vegetables. (25)
2. Insoluble fiber
Insoluble fiber is the type of fiber that does not dissolve in water. It provides bulk and softens stools, helping promote digestive regularity. (14) You’ll find insoluble fiber in wheat bran, whole grains, and certain vegetables. (25)
What is the role of fiber in our diet?
Even though we don’t digest fiber, it still plays an important role in our digestion. Fiber is probably best known for helping relieve constipation, and research confirms what we know intuitively—fiber does make you more regular. (30)
But recent research is beginning to reveal that the health effects of fiber extend beyond digestion.
We now know that fiber has more far-reaching health effects, lowering the risk of several diseases and even the risk of dying from any cause. (31) Research also suggests that low fiber intake, common in Western dietary patterns, may be associated with a greater risk of inflammation and susceptibility to pathogens. (26)
Certain types of fiber, known as prebiotics, also play an important role in overall health by acting as a source of fuel for the beneficial microbes in the digestive system. These microbes, known collectively as the microbiome, play a role in various body functions, including digestion, immunity, metabolism, and neurological function. (26)
Health benefits of fiber
The research is clear and abundant—fiber is good for you. In fact, a database maintained by the International Life Science Institute contains over 1,000 published manuscripts on the health effects of fiber. (11)
Here are just a few areas of health that may benefit from increased fiber in your diet:
- Cardiovascular health
- Digestive health
- Metabolic health (20)
1. Fiber for digestive health
As we’ve noted, fiber plays an important role in digestive health. But it doesn’t just relieve constipation. It can also help with loose stools by absorbing water from the stool and making it bulkier. (13)
2. Fiber for heart health
A diet composed of ultra-processed foods, which are notoriously low in fiber, is a recipe for increasing cardiovascular disease risk. (21) A high-fiber diet, on the other hand, has been shown to protect the heart. (27)
One of the ways that fiber, especially soluble fiber, helps heart health is by lowering total and low-density lipoprotein (LDL) cholesterol levels. (2) Fiber may also lower blood pressure and reduce inflammation. (1)(18)
3. Fiber for weight loss
Another way that fiber can benefit your overall health is by making it easier to maintain a healthy weight. Since fiber is bulky but low in calories, it can help you feel fuller for longer and reduce your calorie intake. (8)(12)
Research shows that if you’re trying to lose weight, the amount of fiber you eat is directly linked to your chances of success. These weight loss promoting effects are due in part to fiber’s ability to improve satiety and suppress caloric intake in subsequent meals. (15)
4. Fiber and blood sugar management
Blood sugar imbalances are a major health concern worldwide. In fact, experts estimate that there will be more than 550 million cases of diabetes in the world by 2030. (29) Diet is a major factor involved in the development of type 2 diabetes, the most common form of the condition. (28)
One reliable way to reduce diabetes risk is to increase fiber intake. (28) Fiber can also help people keep their diabetes in check by slowing sugar absorption and keeping blood sugar levels steady. (14)
The microbiome may play a role here as well. Research has shown that certain microbes in the digestive tract produce short-chain fatty acids (SCFAs). Butyrate, one type of SCFA, is associated with improved regulation of glucose. Dietary components such as fiber may benefit gut microbiota composition and, as a result, influence the production of SCFAs and an individual’s glucose response. (26)
5. Fiber for metabolic syndrome
Metabolic syndrome is condition diagnosed when you have at least three of these related risk factors:
- Excess belly fat
- High triglycerides
- Low HDL cholesterol
- High blood pressure
- High fasting blood sugar (17)
Having risk factors of metabolic syndrome increases your likelihood of developing several other conditions, including diabetes, heart disease, and stroke, so addressing it as early as possible is very important. (17)
One way to do that is by increasing fiber intake. Which makes sense since fiber intake has been shown to improve weight, cholesterol levels, blood pressure, and blood sugar regulation—all components of metabolic syndrome. (3)
In one study, researchers gave the insoluble fiber inulin to mice who were eating unhealthy, high-fat, low-fiber diets. The diet had caused the mice to gain weight and develop metabolic syndrome. Adding inulin to their diet seemed to protect them against some of the negative effects of the unhealthy diet including the increased risk of metabolic syndrome. (32)
The researchers concluded that, in mice, fermentable fiber intake may protect against metabolic syndrome by providing a source of fuel to healthy microbiota. While these findings can’t be extrapolated to humans with metabolic syndrome, the results suggest that fiber’s effects on intestinal microbiota may benefit metabolic health. (32)
How much fiber do you need in your diet?
Adequate intake of fiber varies based on age and gender. The following table outlines recommended daily intake of dietary fiber by population.
How to get more fiber in your diet
Most Americans are not getting as much fiber as they need. (7) If you want to increase fiber in your diet, the best thing you can do is increase the amount of plant foods you eat. Add more fruits, vegetables, leafy greens, legumes, nuts, whole grains, and seeds to your diet, and you’ll naturally get closer to the recommended intake.
Variety is important too since different foods contain different types of fiber, and they’re all important in maintaining overall health. Plus, the microbiome thrives on variety! (10)
Fiber is naturally found in high amounts in various plant-based foods, including:
- Navy beans, cooked – 19 g per cup
- Split peas, cooked – 16 g per cup
- Kidney beans, cooked – 16 g per cup
- Lentils, cooked – 16 g per cup
- Peas, green, frozen – 14 g per cup
- Blackberries – 8 g per cup
- Raspberries – 8 g per cup
- Barley, pearled, cooked – 6 g per cup
- Brussels sprouts, cooked – 6 g per cup
- Turnip greens, cooked – 5 g per cup
- Mustard greens, cooked – 5 g per cup
- Cauliflower, cooked – 5 g per cup
- Oats, dry – 4 g per ½ cup
- Almonds – 4 g per ¼ cup (1 oz) (23)
The bottom line
Adding fiber to your diet is one of the most effective ways of improving your overall health. It’s key to a healthy heart, weight loss, blood sugar control, and more.
If you’re ready to start adding more fiber to your diet, be sure to take it slowly to avoid experiencing gas, bloating, or intestinal discomfort. Add some extra plant foods to your diet, and be sure to increase your water intake at the same time. Over time you’ll reap the benefits of a high-fiber diet, all while adding more flavor and variety to your plate!
- Aleixandre, A., & Miguel, M. (2016). Dietary fiber and blood pressure control. Food & Function, 7(4), 1864–1871.
- Brown, L., Rosner, B., Willett, W. W., & Sacks, F. M. (1999). Cholesterol-lowering effects of dietary fiber: A meta-analysis. The American Journal of Clinical Nutrition, 69(1), 30–42.
- Chen, J. P., Chen, G. C., Wang, X. P., Qin, L., & Bai, Y. (2017). Dietary fiber and metabolic syndrome: A meta-analysis and review of related mechanisms. Nutrients, 10(1), 24.
- Crowe, F. L., Appleby, P. N., Allen, N. E., & Key, T. J. (2011). Diet and risk of diverticular disease in Oxford cohort of European Prospective Investigation into Cancer and Nutrition (EPIC): Prospective study of British vegetarians and non-vegetarians. BMJ, 343(jul19 4), d4131.
- Dhingra, D., Michael, M., Rajput, H., & Patil, R. T. (2012). Dietary fibre in foods: A review. Journal of Food Science and Technology, 49(3), 255–266.
- Fernandez, M.-L. (2001). Soluble fiber and nondigestible carbohydrate effects on plasma lipids and cardiovascular risk. Current Opinion in Lipidology, 12(1), 35–40.
- Grooms, K. N., Ommerborn, M. J., Pham, D. Q., Djoussé, L., & Clark, C. R. (2013). Dietary fiber intake and cardiometabolic risks among US adults, NHANES 1999-2010. The American Journal of Medicine, 126(12), 1059-1067.e4.
- Hervik, A. K., & Svihus, B. (2019). The Role of Fiber in Energy Balance. Journal of nutrition and metabolism, 2019, 4983657.
- Higuero, T., Abramowitz, L., Castinel, A., Fathallah, N., Hemery, P., Laclotte Duhoux, C., … Vinson-Bonnet, B. (2016). Guidelines for the treatment of hemorrhoids (short report). Journal of Visceral Surgery, 153(3), 213–218.
- Holscher, H. D. (2017). Dietary fiber and prebiotics and the gastrointestinal microbiota. Gut Microbes, 8(2), 172–184.
- International Life Sciences Institute. (n.d.). Dietary Fiber Database. Retrieved February 11, 2020, from https://ilsina.org/our-work/research-tools-open-data/dietary-fiber-database/
- Lambert, J. E., Parnell, J. A., Tunnicliffe, J. M., Han, J., Sturzenegger, T., & Reimer, R. A. (2017). Consuming yellow pea fiber reduces voluntary energy intake and body fat in overweight/obese adults in a 12-week randomized controlled trial. Clinical Nutrition, 36(1), 126–133.
- MedlinePlus. (2021). Fiber. https://medlineplus.gov/ency/article/002470.htm
- McRorie, J. W., Jr., & McKeown, N. M. (2017). Understanding the physics of functional fibers in the gastrointestinal tract: An evidence-based approach to resolving enduring misconceptions about insoluble and soluble fiber. Journal of the Academy of Nutrition and Dietetics, 117(2), 251–264.
- Miketinas, D. C., Bray, G. A., Beyl, R. A., Ryan, D. H., Sacks, F. M., & Champagne, C. M. (2019). Fiber intake predicts weight loss and dietary adherence in adults consuming calorie-restricted diets: The POUNDS Lost (preventing overweight using novel dietary strategies) Study. The Journal of Nutrition, 149(10), 1742–1748.
- National Academy of Sciences. (n.d.). Dietary Reference Intakes: Macronutrients. Retrieved from https://www.nationalacademies.org/our-work/summary-report-of-the-dietary-reference-intakes
- National Heart, Lung, and Blood Institute. (2019, January 30). Metabolic syndrome. Retrieved February 11, 2020, from https://www.nhlbi.nih.gov/health-topics/metabolic-syndrome
- North, C. J., Venter, C. S., & Jerling, J. C. (2009). The effects of dietary fibre on C-reactive protein, an inflammation marker predicting cardiovascular disease. European Journal of Clinical Nutrition, 63(8), 921–933.
- Simpson, H. L., & Campbell, B. J. (2015). Review article: Dietary fibre-microbiota interactions. Alimentary Pharmacology & Therapeutics, 42(2), 158–179.
- Slavin, J. (2013). Fiber and prebiotics: Mechanisms and health benefits. Nutrients, 5(4), 1417–1435.
- Srour, B., Fezeu, L. K., Kesse-Guyot, E., Allès, B., Méjean, C., Andrianasolo, R. M., … Touvier, M. (2019). Ultra-processed food intake and risk of cardiovascular disease: prospective cohort study (NutriNet-Santé). BMJ, l1451.
- Thompson, S. V., Hannon, B. A., An, R., & Holscher, H. D. (2017). Effects of isolated soluble fiber supplementation on body weight, glycemia, and insulinemia in adults with overweight and obesity: a systematic review and meta-analysis of randomized controlled trials. The American Journal of Clinical Nutrition, 106(6), 1514–1528.
- U.S. Department of Agriculture. (n.d.). FoodData central. https://fdc.nal.usda.gov/
- U.S. Department of Health and Human Services, & U.S. Department of Agriculture. (2015). 2015-2020 Dietary Guidelines. Retrieved February 11, 2020, from https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/
- U.S. National Library of Medicine. (2018, June 21). Soluble vs. insoluble fiber. Retrieved February 11, 2020, from https://medlineplus.gov/ency/article/002136.htm
- Valdes, A. M., Walter, J., Segal, E., & Spector, T. D. (2018). Role of the gut microbiota in nutrition and health. BMJ, k2179.
- Veronese, N., Solmi, M., Caruso, M. G., Giannelli, G., Osella, A. R., Evangelou, E., … Tzoulaki, I. (2018). Dietary fiber and health outcomes: An umbrella review of systematic reviews and meta-analyses. The American Journal of Clinical Nutrition, 107(3), 436–444.
- Wang, P.-Y., Fang, J.-C., Gao, Z.-H., Zhang, C., & Xie, S.-Y. (2015). Higher intake of fruits, vegetables or their fiber reduces the risk of type 2 diabetes: A meta-analysis. Journal of Diabetes Investigation, 7(1), 56–69.
- Whiting, D. R., Guariguata, L., Weil, C., & Shaw, J. (2011). IDF Diabetes Atlas: Global estimates of the prevalence of diabetes for 2011 and 2030. Diabetes Research and Clinical Practice, 94(3), 311–321.
- Yang, J. (2012). Effect of dietary fiber on constipation: A meta analysis. World Journal of Gastroenterology, 18(48), 7378.
- Yang, Y., Zhao, L.-G., Wu, Q.-J., Ma, X., & Xiang, Y.-B. (2015). Association between dietary fiber and lower risk of all-cause mortality: A meta-analysis of cohort studies. American Journal of Epidemiology, 181(2), 83–91.
- Zou, J., Chassaing, B., Singh, V., Pellizzon, M., Ricci, M., Fythe, M. D., … Gewirtz, A. T. (2018). Fiber-mediated nourishment of gut microbiota protects against diet-induced obesity by restoring IL-22-mediated colonic health. Cell Host & Microbe, 23(1), 41-53.e4