Australian scientists are redefining the classification of dietary fiber for better health benefits

Australian scientists are redefining the classification of dietary fiber for better health benefits

Australian food scientists have reclassified dietary fiber - beyond just soluble and insoluble - to better guide dietary decisions and promote targeted food products.

Dietary fiber in fruits, vegetables, beans, and whole grains are among the most important food components for human health. They help with digestion, weight management, blood sugar control, heart health, cancer prevention and much more.

However, RMIT University food scientist Raj Eri said consumers are consulting on how best to use them for these various benefits.

Just like different medicines target different diseases, so do different types of fibers.

For example, apples and bananas are high in fiber, but the fiber in each works very differently.

Our research helps understand what type of fiber we should eat to address specific ailments. “

Professor Raj Eri, Food Scientist, RMIT University

A new model for tailored diets

In a new study published inFood Research International,The RMIT University team proposes a more nuanced classification of fiber based on five key characteristics: backbone structure, water holding capacity, structural charge, fiber matrix and fermentation rate.

Lead author and RMM PhD candidate Christo Opperman said by starting with the key active features of fiber, he took this “bottom-up approach.” The health effects of the individual fibers are described in more detail.

"For example, let's say you want to promote colonic health. In this case, you identify the properties of a fiber as defined by the bottom-up approachPresentthat match your desired outcome – in this case, fermentation rate,” Opperman said.

“Applying this framework can reassure consumers, nutrition sectors, clinicians and nutritional technologists that they will receive their desired health effect, which was previously a vague guessing game.”

Opperman said the RMM team has now taken 20 different types of fiber and studied how it specifically interacts with the microbiome in the gut.

“So far, these types of specific interactions have been underestimated, but with this framework as a start, we are on the verge of a much more useful and detailed understanding,” he said.

A global fiber gap

Eri said there is already a lot of interest among the nutrition community, clinicians and food technologists – and of course consumers – in how to better incorporate fiber into diets.

“In the countries surveyed, including Europe and the United States, every single population was fiber deficient,” Eri said.

“Considering fiber is one of the most important nutrients, this is extremely concerning.”

While the recommended dietary fiber intake is 28-42 grams per day, Americans on average only get 12-14 grams per day and Europeans get 18-24 grams per day.

Beyond soluble and insoluble

The current classification of dietary fibers has grouped them into soluble and insoluble fibers, which is based on whether they dissolve in water.

Insoluble fiber is rarely fermented in the colon and helps us stay regular.

Soluble fiber is more easily fermented and can reduce cholesterol, glucose absorption and food cravings.

But it's not always that easy. For example, fiber that is often insoluble can also rapidly ferment and reduce glucose absorption.

“Despite our evolving understanding of how fiber types are central to supporting a healthy gut biome, our classifications of our dietary fiber remain simple between broad categories of soluble and insoluble types,” said Eri.

“This binary classification of soluble and insoluble classification inadequately captures the diverse structures and complex mechanisms by which dietary fiber influences human physiology.”

“Our framework is an essential step towards addressing this gap,” he said.

The researchers now plan to study how a specific type of fiber (based on our new classification) modulates the microbiota and how we can use such knowledge for specific health applications.

Fiber is an optional “nutrient.”
Fiber is what cows have extra stomachs for.
Humans don't have the mechanisms to break down fiber, so we should eat cows.
Thank God, right?

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