What is Dietary Fiber?
Our Evolving Understanding of Fiber
Advancements in Fiber Testing Methods
The importance of fiber in the human diet has been known directly for thousands of years, and indirectly for probably longer. Until recently, however, the role of fiber was believed to be maintaining regularity and “bulking up” the stool, not exactly the most glamourous functions in the field of health and nutrition. Likewise, the analysis of fiber was relegated to the back burner. I mean, how important was the analysis of that portion of your diet that was destined to end up in the toilet with very little metabolic intervention?
The Fiber Fundamentals
Historically, fiber was known to come from plant sources and was known to be the undigestible fraction of the plants. Comparison of disease patterns between Western societies and less developed African societies also observed a potential link between fiber intake and diseases such as heart disease and certain cancers. During this time, the term “dietary fiber” became accepted, and a working definition was developed. Dietary fiber was now accepted to be the portion of plants that included polysaccharides and lignins and any other plant-based materials that resisted digestion.
This definition allowed methods to be developed to estimate the dietary fiber in food. As a chemist, I like to think that the development of the early fiber method produced better data, which allowed health practitioners to see more clearly the links between fiber and other physiological systems.
The Evolving Understanding of Fiber
The emergence of a working definition of dietary fiber, in turn, led to further refinement of analytical methods and again, more clarity in the health effects. The contribution of soluble forms of fiber has become critical to the proper analysis and also the impact on health. Now, the widely accepted benefits of a high fiber diet, include (in addition to the long-accepted toilet benefits) reduction of colorectal cancers, control of cholesterol, blood sugar, and weight, as well as an overall increase in lifespan.
Further investigation into the contribution of fermentable forms of fiber may provide evidence of reduction of inflammation and the associated pathologies, as well as binding and clearance of toxins. In addition, there may be evidence of a production of short chain fatty acids, maintenance of a healthy gut flora population that may affect the immune system, and a myriad of other suspected but not yet proven benefits.
How Much Fiber Is Actually In My Product?
Contingent on the investigation of these health benefits is a need for continued advancement in the analytical methods realm. There is an ongoing drive in the analytical chemistry community for robust and specific analytical methods to both accurately capture all forms of dietary fiber, as well as allow for quantification of specific fractions to allow formulations that may target specific health benefits.
Modern testing methodologies emerged in the 1980s with a focus on an enzymatic-gravimetric technique that summed soluble and insoluble polysaccharides as a total dietary fiber value. This method was soon improved to be able to determine total, insoluble, and soluble fibers separately to allow for more specific label declarations.
The 2000s saw the emergence of isolated fibers such as inulin and various resistant starches, further driving innovation in the analytical testing world. Consequently, many more methods emerged with various refinements to allow for closer alignment to how the human body processes various polysaccharides.
Two notable methods arrived in 2009 and 2011, following the release of an official definition of dietary fiber by CODEX Alimentarius Commission that aimed to recognize the many substances that behave like dietary fiber regardless of their source. As the definition of fiber continues to evolve within both regulatory and scientific communities, analytical testing stakeholders will certainly be paying close attention.
Mérieux NutriSciences is able to help navigate the complex fiber landscape for food manufacturers. We offer a thorough catalog of dietary fiber testing capabilities that aims to capture approved dietary fibers in most matrices, including inulins and other recognized polysaccharides. Contact our experts today to help understand the best testing approach for your product.
In case you missed our webinar, Dietary Fiber: More Than Something to Chew On, April 1st, 2020 at 11 AM CST with Walt Brandl to learn more about dietary fiber, click here to view the recording.