The Health Benefits of Prebiotic Fiber

What science says about the importance of prebiotic fibre, with evidence-based research on 5 different types

Although all prebiotics are fiber, not all fiber is prebiotic!

This means that on top of making sure that you’re getting enough fiber in general, it can also be highly important to ensure that you’re also getting the right types of fiber, too.

In fact, a plethora of scientific and nutritional research suggests that an adequate consumption of prebiotic fiber can make all the difference between supporting the healthy functioning of your immune system, or impeding it.

However, in order for a fiber to be considered prebiotic, it has to fulfil three core requirements (1):

  • that it is not digestible by the small intestine
  • that it is fermented and used by good bacteria within the microbiome
  • that it produces measurable benefits to health and well-being

What is the microbiome?

The microbiome is the name for the collaborative system of micro-organisms that covers our bodies from head to toe. These micro-organisms include bacteria, archaea, viruses, and fungi, and are responsible for 99% of the total genetic information we contain as human beings!

The highest concentration of microbes (around 100 trillion) resides in our gastrointestinal tract, aka the gut. When the bacteria in our gut receives the correct nourishment (aka prebiotic fiber), they become well-equipped to support a healthy immune system by converting these fibers into a compound referred to as short-chain fatty acids (SCFA)(2).

A greater rate of conversion for SCFA is linked specifically to a large range of healing implications, such as the reversal of insulin resistance, leaky gut, high cholesterol, as well as overall digestive function, disease immunity, and even a better mood (3, 4, 5).

For this reason, it makes sense that the foods we eat can have one of the single greatest impacts (next to only antibiotics and disease) on the health of our microbiome — and therefore, the health of our entire body, too!

This article will cover 5 different types of fiber, each with their own set of prebiotic effects and implications within the body:

  • Guar Gum
  • Larch Arabinogalactan
  • Fructo-Oligosaccharides (FOS)
  • Pectin
  • Chicory Inulin

Guar Gum

Guar gum — also frequently packaged as Partially Hydrolyzed Guar Gum, or PHGG — is a powdery, white, taste-less, water-soluble, natural dietary fiber made from guar beans, aka cluster beans.

Research on guar gum demonstrates its high effectiveness as a prebiotic through the promotion of growth in helpful bacteria such as lactobacilli and bifidobacteria, as well as increasing the presence of SCFA within the gastrointestinal tract (6).

These microbial reinforcements then work to strengthen the immune system, reduce bloating, and decrease the risk of potentially fatal diseases, as well as reduce symptoms for individuals who may suffer from digestive disorders such as IBS (7, 8).

These effects occur as a result of the fermentation process, that allows for the guar gum fibre to be converted into SCFA and used as an energy source for the type of cells — namely, epithelial cells — that are necessary for the regulation of metabolism, gut physiology, and immunity, among other vital processes (9).

Larch Arabinogalactan

This type of prebiotic fibre, arabinogalactan, has been eaten by humans for thousands of years and has earned approval by the FDA for its impressive and widely studied list of health advantages.

Arabinogalactan can be found in high quantities in the seeds, fruit, leaves, roots, and sap of a wide variety of different plants, with the most common commercial source of arabinogalactan derived from the North American larch tree pictured above (10).

When it comes to larch arabinogalactan’s impact on the body when consumed, research suggests that this prebiotic plays such a functional role in supporting the immune-system that it can even decrease the occurrence of common cold infenctions by up to 23% (11).

Further to this, numerous studies have also found larch arabinogalactan to be successful at promoting and protecting health on a cellular level, such as through the enhancement of natural killer (NK) cells, macrophages, and pro-inflammatory cytokines — all mechanisms designed to readily fight and prevent chronic disease (12).

Fructo-Oligosaccharides (FOS)

One of the most potent and commonly found type of prebiotic fiber is one known as fructo-oligosaccharides — and thankfully — FOS, for short.

FOS is comprised of short fructose chains, with a mildly sweet flavor profile. But, unlike other sweeteners, FOS has no impact on blood glucose levels, as a result of its indigestibility as a prebiotic fiber, which means it won’t contribute to a spike in insulin.

Even at fairly low levels of consumption (ranging between 5–8 grams per day), FOS has been linked to a significant increase in bifidobacteria activity within the colon, directly helping to maintain the balance of the gut microbiome (13).

If you’re looking for dietary sources of FOS, foods such as bananas, chicory root, artichoke, garlic, and asparagus are all known to contain relatively high amounts of this prebiotic fiber (14)!


Pectin is another type of water-soluble prebiotic fibre that supports a variety of vital functions within the body. For example, research shows that pectin helps to reduce the glycemic response of the body by stalling the absorption of glucose, and has also been linked to the lowering of LDL cholesterol and the risk of heart disease (15).

Interestingly enough, when pectin fibre reaches our gastrointestinal tract, it has the unique ability to be very quickly metabolized and fermented by the bacteria within our gut, that then converts it into short-chain fatty acids (SCFA) to be absorbed back into the bloodstream (16).

When this occurs, not only does it have the potential to reduce and control appetite, but it also allows our immune system to become stronger by feeding the type of bacteria in our gut that are designed to effectively process fatty acids from the foods we eat (17).

Pectin can be found in relatively large qualities in a variety of different whole foods such as apples, strawberries, potatoes, carrots, lemons, and even some legumes and nuts!

Chicory Inulin

One of the best sources of the prebiotic fiber, inulin, comes from the root of the chicory plant. Chicory has a long history of medicinal and nutritional usage that can be traced back as far as the Roman Empire and Ancient Egypt.

Chicory has such an incredible reputation as a prebiotic fiber, namely due to the fact that fiber comprises nearly 90% of its weight when dry, making it an excellent source of food for bacteria within the microbiome (18).

As well as containing other types of fibre such as pectin and (hemi-)cellulose, chicory root is extremely high in one particular prebiotic fiber called inulin. Inulin has been rigorously studied for its positive association with energetic metabolism, insulin sensitivity, as well as a lowering of cholesterol (19, 20).

In addition to the effects outlined above that help to moderate appetite, increase digestive efficiency, and prevent the development of diseases such as type-2 diabetes and coronary heart diseases, research suggests that inulin from the chicory root may also exhibit qualities that aid in the protection of oxidative stress (21).


Prebiotic fiber is a nutrient our body (rightfully) knows how to take very seriously. From strengthening our immune system, to preventing pathogens and a build-up of free radicals from encouraging both short-term and chronic disease — prebiotics have our back.

The more we sponsor the right kind of microbial environment within our gut through the foods we eat and the supplements we take, the more our bodies reward us by continuing to foster our overall, and on-going well-being.

From a bacterial perspective, that’s why adding prebiotics fiber to your diet and daily routine can be considered a key step in providing your body with the best possible health outcomes!

Originally published at on March 26, 2021.

Writer and published author with an international background in psychology, nutrition, and creative writing. I’m just here to learn ;)

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