Scientists uncover the secret language of dietary fiber

Both the humble bananas and apples sitting in fruit bowls may contain fiber, but Australian scientists have found that their fiber type speaks completely differently to your body.

This revelation comes from food scientists at RMIT University who have developed a more complex dietary fiber classification system that goes beyond traditional soluble and insoluble categories, a breakthrough that can change how we address specific health issues in nutrition.

“How different drugs target different diseases, so do different types of fiber,” said Professor Raj Eri, a food scientist at RMIT University. “For example, both apples and bananas are rich in dietary fiber, but the fibers for each piece are very different.”

The study, published on January 31 in International Food Research, introduces a framework for classification of fibers based on five key characteristics: backbone structure, capacity, structural charge, fiber matrix and fermentation rate.

This reclassification is important because dietary fiber (containing fruits, vegetables, beans and whole grains) is crucial for multiple aspects of health, including digestion, weight management, blood sugar control, heart health and cancer prevention. However, personalized guidelines for using different fiber types are surprisingly limited for specific health benefits, according to the researchers.

From binary to synthesis

For decades, nutritionists have divided dietary fiber into two groups: soluble (dissolved in water) and insoluble (insoluble in water). Although this simplification makes fibers easy to understand, it cannot capture the complex ways in which different fibers interact with our bodies.

“Although our growing understanding of how different types of fibers at the core cultivate healthy gut biogroups, our dietary fiber classification remains simple between a wide range of soluble and insoluble types,” explains Eri. “This binary classification of soluble and insoluble is not sufficient to capture the various structures and complex mechanisms that dietary fiber affects human physiology.”

Traditional models show that insoluble fiber mainly contributes to regularity, while soluble fiber reduces cholesterol and glucose absorption. But the reality is even more subtle – the determined insoluble fibers can ferment quickly and reduce glucose absorption, thus contradicting their typical classification.

Decompose the new system

The team’s new “bottom-up approach” examines fibers at a more basic level. Lead writer and RMIT PhD candidate Christo Opperman explains that their framework begins with the key active characteristics of fiber, a function that is consistent with specific health outcomes.

“For example, let’s say you want to promote colon health. In this case, you determine the properties of the fiber defined by a bottom-up approach, and the bottom-up approach aligns with the results you need – in this case the fermentation rate.”

The new classification considers features such as whether the fiber is linear or branched, its charge, how water holds water and the fermentation rate of intestinal bacteria, which directly affects the function of the fiber in the body.

“Applying this framework can ensure that consumers, nutritionists, clinicians and food technicians are receiving the desired health effects, which was previously a vague guessing game,” Opperman added.

Global fiber gap

This reclassification is at critical times. Current dietary data show information about “fiber gap” in many populations.

“In countries surveyed, including Europe and the United States, every population has a shortage of fiber,” Eri noted. “This is extremely worrying given that fiber is one of the most important nutrients.”

Although health authorities recommend consuming 28-42 grams of fiber per day, the average Americans are only 12-14 grams per day, while Europeans are slightly better every day, slightly higher than 18-24 grams per day.

The researchers believe that their framework can help address this gap by making fiber recommendations more precise and effective, thereby encouraging specific fibers to obtain targeted health benefits.

From research to practical application

To demonstrate the practical value of its model, the team has begun mapping out specific interactions between different fiber types and the gut microbiota.

“The RMIT team now takes 20 different types of fibers and looks at how they interact specifically with the microbiome in the gut,” explains Opperman. “So far, these types of specific interactions have been studied, but since this framework is a start, we are on the verge of a more helpful and detailed understanding.”

This study may ultimately lead to more personalized nutritional advice and improve functional foods targeting specific health needs.

For everyday consumers, meaning may be important. We may end up choosing foods with specific fiber profiles to address specific health issues rather than simply seeking high-fiber foods, whether it’s blood sugar management, cholesterol lowering or digestive health.

Researchers are now planning to further investigate how specific fiber types regulate gut microbiota and how this knowledge can be applied to specific health conditions.

“Our framework is an important step in addressing this gap,” Eri said, noting the future implications of this more nuanced approach to one of our most important but often overlooked nutrients.

With the continuous development of nutritional science, this study shows that understanding the language of fiber may be the key to unlocking its full potential for human health – fiber fiber benefits.