by Angelina Masalov, Grand Canyon University Dietetic Intern
The push to eat more fiber has recently gained popularity as a major health and wellness trend. This is a great influence as it encourages more people to eat plant foods like fruits and vegetables. However, knowing how to do so correctly and understanding how much your body can tolerate is just as important to achieve the health benefits you are after. Let’s look at what you need to know about dietary fiber, the science behind popular supplements like psyllium husk and Benefiber, and the side effects to keep in mind before hopping on this trend.
Why Your Gut Needs Fiber
To understand fiber, it helps to start with the basics. Dietary fiber consists of the edible parts of plants that the human body is unable to digest. Because our natural enzymes cannot break it down, it passes through our digestive system without actually being absorbed into the bloodstream. All the hype you hear about the benefits of fiber comes from the work it does while in the gut. It helps move food through the intestines, feeds the trillions of tiny bacteria that live inside our gut, and helps you feel full for longer. These functions are super important for our gut health, which in turn supports our overall health and wellbeing.
The Different Types of Fiber
Now that we know what fiber is, the next step is understanding that not all fiber is the same. The two main types are soluble and insoluble fiber. Most plant foods, such as whole grains and fruits and vegetables with the skin, contain a mix of both.
Each fiber also carries different characteristics that allow it to behave differently in the body. Two key traits to know are whether a fiber is viscous (meaning it thickens and forms a gel) and whether it is fermentable (meaning gut bacteria can break it down, which produces gas). Understanding these differences helps you choose what works best for your digestive needs.
Soluble Fiber: The Gel-Maker
Soluble fiber dissolves in water to form a gel-like substance in your digestive tract. This helps slow down digestion and softens stools. Because of this gel-forming action, it can help manage both constipation and diarrhea, though it is often especially helpful for firming up loose stools (3).
This type of fiber tends to be gentler on sensitive stomachs, making it a common choice for people dealing with flare-ups of Inflammatory Bowel Disease (IBD) or sensitive gut conditions (3).
Common food sources with mostly soluble fiber include oatmeal, barley, bananas, applesauce, avocados, chia seeds, and peeled fruits or vegetables.
Insoluble Fiber: The Broom
Insoluble fiber does not dissolve in water. Instead, it acts like a broom, pulling water and adding physical bulk to your stool. This helps speed up the transit of waste, “sweeping” it through the intestines. It is especially effective at preventing and relieving constipation (3).
Common food sources include cabbage, legumes (beans and lentils), brown rice, whole wheat, seeds, leafy greens, popcorn, and fruits and vegetables with the skin.
Psyllium Husk Fiber Supplement
Psyllium husk comes from milling the seeds of a plant called Plantago ovata. It is mostly composed of dietary fiber and contains small amounts of various other nutrients. In comparison to other plant foods, psyllium husk naturally has the highest amounts of a very specific type of soluble fiber called arabinoxylan (1).
Because of its unique structure, gut bacteria cannot break this fiber down easily. It is mostly a soluble fiber that is highly viscous and non-fermentable (1, 2). This means you get all the mechanical benefits of a soluble fiber without it being digested by gut bacteria and producing gas. Because of this thickening, gel-forming action, its benefits include lowering cholesterol levels, slowing down digestion to help you feel fuller for longer, and lowering blood sugar spikes (1, 2). This supplement is a gentle, tolerable option to help move food through the intestines for individuals with sensitive guts. However, because it is non-fermentable, it does not provide the benefit of feeding the gut bacteria.
Benefiber (Wheat Dextrin) Supplement
Benefiber is another popular supplement that comes in many forms, such as gummies, tablets, and powder. Most of the benefits you get from this supplement come from a specific type of fiber called wheat dextrin. Wheat dextrin is a byproduct of wheat starch that is processed into a powder that can be added to food products, chewables, and capsules (4).
Wheat dextrin is a soluble fiber that is highly fermentable, but it does not form a gel when mixed with water (non-viscous). This means it acts as excellent food for the gut bacteria, which may cause gas and bloating as a result (4). However, because it is non-viscous, it does not provide the mechanical benefits of sweeping food contents through the intestines the way a gel would.
How to Add Fiber Without the Bloat
Stomach discomfort can be a common side effect of eating fiber. As mentioned earlier, certain fibers can cause gas, bloating, stomach cramps, and sometimes even diarrhea. These effects can be triggered, or even worsened, if too much fiber is consumed all at once without gradually building up to that amount (1, 4). To prevent discomfort, the recommendation is to start small and gradually increase your intake to an amount your body can tolerate (4). Additionally, fiber relies on water to do its job. Eating fiber without drinking enough water puts you at risk of experiencing these stomach pains. It is highly important to increase your fluid intake when eating fiber-rich foods or supplements (1, 4).
Fiber Supplements or Plant Foods?
Eating more fiber provides incredible health benefits to your metabolic and gut health, whether it comes from plant foods or supplements. In fact, not eating enough fiber can contribute to the development of many conditions, including diabetes, high blood pressure, and heart disease. The U.S. Department of Agriculture (USDA) emphasizes that the average American does not consume nearly as much fiber as recommended (5). Furthermore, a 2025 CDC report shows that ultra-processed foods make up 55% of the calories in Americans’ diets (6).
The ultimate goal is to push for eating more whole plant foods to increase fiber. However, it is important to be realistic. Given the convenience and affordability of the standard American diet, expecting everyone to suddenly eat large amounts of fruits and vegetables regularly might not be realistic. Therefore, fiber supplements can be a highly effective tool to help bridge the fiber gap and improve public health.
If you are needing help figuring out your own personal fiber needs, don’t hesitate to reach out. That’s what we are here for at Food 4 Success!
References:
(1) Geremew Kassa, M., Alemu Teferi, D., Asemu, A. M., Belachew, M. T., Satheesh, N., Abera, B. D., & Erku, E. G. (2024). Review on psyllium husk: nutritional, functional, health benefits, food industry applications, waste treatment, and potential negative effects. CyTA – Journal of Food, 22(1), Article 2409174. https://doi.org/10.1080/19476337.2024.2409174
(2) Gibb, R. D., Sloan, K. J., & McRorie, J. W. (2023). Psyllium is a natural nonfermented gel-forming fiber that is effective for weight loss: A comprehensive review and meta-analysis. Journal of the American Association of Nurse Practitioners, 35(8), 468–476. https://doi.org/10.1097/JXX.0000000000000882
(3) Kane, K., & Prelack, K. (2019). Advanced medical nutrition therapy. Jones & Bartlett Learning.
(4) Liu, I. (2025, August 23). Benefiber how does it work. Elearning. https://elearning.asc.edu.ag/benefiber-work
(5) USDA Economic Research Service. (2023, March 28). Over time, racial and ethnic gaps in dietary fiber consumption per 1,000 calories have narrowed. U.S. Department of Agriculture.
(6) Williams, A. M., Couch, C. A., Emmerich, S. D., & Ogburn, D. F. (2025). Ultra-processed food consumption in youth and adults: United States, August 2021–August 2023 (NCHS Data Brief No. 536). National Center for Health Statistics. https://doi.org/10.15620/cdc/174612
