Understanding fiber intolerance: why soluble corn fiber matters for food product development
Written by: Melissa Kaczmarczyk, Principal Scientist, Global Nutrition and Maanvi Maheshwari, Scientist, R&D Fibers, Science & Innovation
Let’s be honest; fiber has a reputation problem.
Most people know they should be getting more of it, but for many, that’s where the story ends. It’s often associated with digestive discomfort, and something you add to your diet, or take as a supplement, because you’re “supposed to.”
But one of the most important things to know is that not all fiber behaves the same. And once you begin digging into that, a lot of the confusion around tolerance—and understanding of fiber’s role in the diet—begins to make more sense.
“Fiber” isn’t one thing
Fiber is often spoken about as if it’s a single ingredient. Consumers can be forgiven for thinking this way; most nutrition labels simply list “Fiber” (if there is any) followed by a weight and the percentage of the daily value.
Dietary fibers are carbohydrate polymers, meaning they are (without getting too technical) large molecules made of smaller pieces linked together in a long chain. What separates them from other carbohydrates is that they pass through the small intestine and reach the colon undigested.
At a basic level, fibers are typically split into two groups: soluble and insoluble. That’s a useful way to start thinking about them, but it only scratches the surface. Within those categories, fibers can vary significantly in how they interact with the body. In the scientific community, we talk about a range of solubility, a spectrum from soluble to insoluble, with varying degrees of fermentability and viscosity.
Understanding that difference is key, because once fiber reaches the gut, it doesn’t just sit there. It starts interacting with a very active, very important ecosystem.
What’s happening in the gut when we eat fiber
If you think of the colon as a bustling city, the gut bacteria are the residents, and they need a steady food supply. Fiber is what feeds them. As those bacteria break fiber down through fermentation, they produce short-chain fatty acids (SCFAs) which help support gut health and contribute to benefits beyond digestion. Fiber also contributes to stool bulk and regularity—not glamorous, but extremely good for the body. In general, insoluble fiber contributes more to bulking, and soluble fiber is more readily fermented.
The fermentation process supports gut health and produces compounds like short-chain fatty acids, which play a role well beyond digestion. These compounds interact with systems throughout the body, contributing to all-over health. (Including in some surprising ways, which we’ll touch on later.)
Why some fibers can cause digestive discomfort
This is where fiber’s reputation starts to come into play.
One of the biggest differences between fibers is how quickly they ferment. Shorter-chain fibers, including inulin and fructooligosaccharides (FOS), break down more quickly and earlier in the colon1. At higher intake levels—particularly when consumed well above daily recommendations—this faster fermentation can contribute to increased gas production, which is why some people associate large amounts of certain fibers with digestive discomfort.
Other fibers, like polydextrose and soluble corn fiber, behave differently. They break down more slowly, over a longer stretch of the colon2. From a practical standpoint, that matters. A more gradual process can mean fewer spikes in gas production, a more consistent gut response, even when consumed at high levels (thank you #fibermaxxxing for getting people eating more fiber) and ultimately a more pleasant experience3. So, when we talk about “fiber tolerance,” we’re really talking about how structure influences fermentation, and how that translates into how people feel.
For anyone who’s ever wondered why one fiber-rich product feels fine, and another doesn’t, this is often the reason. It’s not “fiber”; it’s the kind of fiber, the amount of that fiber, and what your body does with it that makes the difference.
Health benefits beyond digestion
Ongoing research into dietary fiber is expanding our understanding of the scope of its potential benefits.
As we alluded to earlier, it goes far beyond digestion. The compounds produced during fermentation don’t just stay in the gut — they can influence other systems, including the brain4.
In a recent clinical study, adults consumed 18g of PROMITOR® soluble fiber daily and underwent a series of cognitive tests alongside measurements of their gut microbiome5. The idea was to better understand how changes in the gut might connect to how we think and process information.
What researchers found was a measurable improvement in memory and certain aspects of attention. Participants were able to respond more quickly and maintain focus more effectively during specific tasks. At the same time, there were shifts in gut bacteria, specifically an increase in Parabacteroides, bacteria associated with possible anti-inflammatory and gut barrier properties, plus compounds that may contribute to gut-brain communication and health.
These findings are specific rather than sweeping — not every aspect of cognition changed — but they provide more evidence toward a growing body of research in understanding of the gut–brain connection. They also highlight something important: when fiber-rich products are designed to interact with the gut in a particular way, the effects may extend further than we once thought.
Taking a more informed approach to fiber
All dietary fiber is important for your body, and an even mix of different kinds is optimal6. The best way to achieve this is through a balanced diet rich in whole foods. But there is an opportunity to deliver fiber-rich products that meet the needs of modern life, taste great, and are better tolerated by more consumers. This enables bolder fortification and helps consumers to close the fiber gap with fewer habit changes.
That means successfully incorporating fiber into foods people actually want to eat. From a formulation standpoint, that requires balancing functionality with consumer experience. Fiber needs to deliver its benefits without creating new problems; no off notes, no unwanted thickness, no compromise on texture.
This is where our expertise in formulation and an ingredient like PROMITOR® soluble fiber really makes a difference. Soluble corn fiber is a medium- to long-chain fiber, supporting more gradual fermentation along the colon that’s associated with better tolerance. At the same time, it brings a set of functional benefits that make it easier to work with: it dissolves cleanly, has low viscosity, and contributes minimal flavor.
Because of all these positive attributes, we can add it to a wide range of products without changing how they taste or feel. This eliminates the need to add masking agents or other ingredients to compensate, keeping labels cleaner and formulations simpler. Your consumers are unlikely to notice it, due to its clean taste, but it’s there, helping close the fiber gap in a way that fits seamlessly into everyday eating habits. And you can typically incorporate it with minimal or no changes to your existing process.
Making fiber-rich products a daily ritual, not just an obligation
Protein is a marketing success story. It’s available in practically every format, even cold foam on top of your coffee. Consumers associate it with fitness and building muscle. As a result, there is no protein gap among American consumers.
But there is a fiber gap. Depending on factors such as age and gender, we should have a goal of 25 to 38 grams of dietary fiber each day7. The current average in the U.S. is 16.6 grams. Clearly, fiber isn’t going away as a topic. If anything, it’s becoming more relevant.
We spoke about an opportunity before, and here it is. It’s no longer about getting more fiber at any cost. Getting it from whole foods alone may cause a significant calorie increase for most consumers as well as difficult to integrate habit changes8. There’s also a perception issue, where previous generations’ high-fiber products may have been bland, chewy or gritty. It’s about getting the right kinds of fiber, in balanced amounts, ones that work with the body and deliver benefits without discomfort. Beyond that, we can formulate products that taste delicious and support outcomes outside how consumers traditionally view fiber, like reduced sugar and slower glucose release to avoid spikes.
A couple of our most recent prototypes are fiber-fortified Veggie Snackers and a high-protein high-fiber chocolate shake. The veggie snackers are made with PROMITOR® soluble fiber, delivering 6 grams of dietary fiber in each delicious serving. These are both excellent examples of how we can incorporate fiber into everyday products that are enjoyable to eat and help fiber reach consumers that are looking for small nudges towards health forward choices.
Let’s keep the fiber conversation moving
Understanding fiber is one thing. Applying that understanding effectively is another.
A “good source” claim may be achieved at relatively low fiber levels, but the daily intake levels needed to deliver meaningful health benefits can be significantly higher. As formulators increase fiber levels to close the fiber gap and deliver real benefits, digestive tolerance becomes critical—especially as consumers often combine multiple fiber‑fortified products across the day.
Choosing fibers with proven tolerance gives manufacturers the confidence to fortify more boldly. With PROMITOR® soluble fiber, for example, 10g per day has been shown to support calcium absorption and bone health9-11, while still offering a wide tolerance margin. That tolerance provides peace of mind: consumers get the benefit whether they have one product or several, without digestive discomfort.
That tolerance provides peace of mind for formulators: whether you want to fortify your product with the full amount of fiber to deliver the studied benefit or the full amount of fiber to close the fiber gap in your region, you want to ensure you have peace of mind about tolerance in case the consumer likes your product so much that they have several in a day.
Whether it’s in a beverage, a snack, or a nutrition bar, the goal is the same: put fiber into foods people already enjoy, while preserving mouthfeel and prioritizing incredible taste. Together, we can make better nutrition simpler and more accessible and begin to close the fiber gap.
Talk to our fiber experts about how PROMITOR® soluble fiber — and the wider range of ingredients we work with — can help you create better-tolerated, great-tasting products that fit into everyday life.
Footnotes
1-2. Housez, B., Cazaubiel, M., Vergara, C., Bard, J.‑M., Adam, A., Einerhand, A., & Samuel, P. (2012). Evaluation of digestive tolerance of a soluble corn fibre. Journal of Human Nutrition and Dietetics, 25(5), 488–496. https://doi.org/10.1111/j.1365-277X.2012.01252.x
3. Jones, J. M. (2014). CODEX‑aligned dietary fiber definitions help to bridge the “fiber gap.” Nutrition Journal, 13, 34.
4. Dalile, B., Van Oudenhove, L., Vervliet, B., & Verbeke, K. (2019). The role of short‑chain fatty acids in microbiota–gut–brain communication. Nature Reviews Gastroenterology & Hepatology, 16(8), 461–478. https://doi.org/10.1038/s41575-019-0157-3
5. Tate & Lyle. (n.d.). New clinical evidence helps explain how soluble corn fibre may support cognitive function. https://www.tateandlyle.com/news/new-clinical-evidence-helps-explain-how-soluble-corn-fibre-may-support-cognitive-function
6. Slavin, J. (2013). Fiber and prebiotics: Mechanisms and health benefits. Nutrients, 5, 1417–1435.
7. National Academies of Sciences, Engineering, and Medicine. (2005). Dietary Reference Intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. https://nap.nationalacademies.org/read/10490/chapter/1 (Accessed June 24, 2024).
8.Nicklas, T. A., O’Neil, C. E., Liska, D. J., Almeida, N. G., & Fulgoni, V. L. (2011). Modeling dietary fiber intakes in US adults: Implications for public policy. Food and Nutrition Sciences, 2(9), 925–931. https://doi.org/10.4236/fns.2011.29126
9. Whisner, C. M., et al. (2014). Soluble maize fibre affects short‑term calcium absorption in adolescents. British Journal of Nutrition, 112, 446–456.
10. Whisner, C. M., et al. (2016). Soluble corn fiber increases calcium absorption associated with shifts in the gut microbiome. Journal of Nutrition, 146, 1298–1306.
11. Jakeman, S. A., et al. (2016). Soluble corn fiber increases bone calcium retention in postmenopausal women. American Journal of Clinical Nutrition, 104, 837–843.