Distinguishing between prebiotics and dietary fibers

In the realm of nutrition and health, the terms "dietary fibers" and "prebiotics" are often used interchangeably, though they represent distinct concepts with overlapping characteristics. While both are recognized for their significant health benefits, a deeper understanding of their differences shows the unique roles they play in promoting well-being. This article explores the details of dietary fibers and prebiotics, explaining what they are and their specific contributions to our health, focusing on the remarkable properties of chicory inulin and oligofructose.

Dietary fibers and their health benefits

Most of us are familiar with the concept of dietary fibers. These fibers originate from plant-based food sources and can be found in fruits, vegetables, legumes, and other plant material. The exact definition of dietary fibers is described by regulatory organizations and slightly differs between countries, though most definitions include ‘non-digestible carbohydrate’ with a ‘beneficial physiological effect’. In developed countries, the consumption of dietary fiber is currently below recommendations from government health organizations, creating a so called ‘fiber gap’, i.e. a difference between the daily recommendations and the actual intake. This is a missed opportunity since dietary fibers are well-known for their positive influence on health and well-being. They improve digestive health by adding bulk to stool and supporting regular bowel movements, they support weight reduction as high-fiber foods tent to be more filling which can help control appetite, and they are implicated in various other benefits such as reducing stress and cardiovascular diseases. It is less well-known that some special dietary fibers may also be classified as prebiotics.

Prebiotics: nourishing gut health

The International Scientific Association for Probiotics and Prebiotics (ISAPP) defines a prebiotic as ‘a substrate that is selectively utilized by host microorganisms conferring a health benefit’. Selectivity means that a prebiotic must be used by only one or several friendly microbes present in the intestine, but not all. Furthermore, a prebiotic must show a health benefit that is scientifically proven and supported by well-conducted human research studies. Inulin and oligofructose extracted from the roots of the chicory plant are among the few ingredients, and the only plant-based ones, that are officially recognized as prebiotics by ISAPP. In addition, they are also dietary fibers, i.e. chicory root fiber.

Difference between a fiber and a prebiotic

As explained above both the definition of dietary fibers as well as prebiotics include a ‘beneficial physiological effect’ or a ‘health benefit’. The difference between them, is that for prebiotics this health benefit should be conferred by a selective effect on the microbiota.

Chicory inulin and oligofructose reach the human colon without being digested. In the colon, bifidobacteria ferment them as energy source, producing short chain fatty acids (SCFAs), while growing and increasing in number. This selective fermentation of chicory inulin and oligofructose by bifidobacteria, the so-called ‘bifidogenic effect’, is key to the health benefits. The SCFAs are absorbed and utilized as an energy source by the entire body. Especially the colon cells will function better, supporting a regular digestion with softer stools, and improving protection against chemicals and pathogens. Furthermore, there is science that chicory root fiber can play a role in reducing inflammation which underlies may conditions in today’s society.

Conclusion

Dietary fibers from plant food sources are not digested in the small intestine and reach the colon intact where they are fermented by the intestinal microbes. Some dietary fibers, such as chicory inulin and oligofructose, are selectively fermented by the beneficial bifidobacteria resulting in health benefits, classifying them as prebiotics. Chicory inulin and oligofructose are the only plant-based prebiotic ingredients officially recognized by ISAPP that are available on the market. The prebiotic effect occurs through the fermentation of chicory root fibers by bifidobacteria in the gut, leading to the production of SCFAs. Everyone can benefit from the prebiotic effects of chicory root fiber, as numerous studies have demonstrated the bifidogenic effect from infants to elderly, which strongly underlies a healthy gut and well-being.

In summary, while dietary fibers benefit overall health, prebiotics specially nurture our gut microbiota, leading to a cascade of positive effects.

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