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Prebiotics, what are they for and why should you take them?

Prebiotics, what are they for and why should you take them?

Published: 11 August, 2023 - Updated: 10 November, 2023 | 4'

What are prebiotics?

A prebiotic is defined by the FAO as "a non-viable food component that confers a health benefit on the host associated with microbiota modulation".

This definition arose from the observation that indigestible plant fibers cause a specific modulation of the intestinal microbiota, particularly an increase in the number of bifidobacteria and/or lactobacilli, or a decrease in potentially harmful bacteria.

Benefits of prebiotics

Among the benefits of prebiotics are:

  • Their fermentation produces short-chain fatty acids that are specific nutrients for intestinal tissue, in addition to modulating the metabolic byproducts produced by the breakdown of amino acids.
  • Increased fecal weight and modulation of pH in the colon.
  • Reduction in the concentration of putrefactive, toxic, mutagenic or genotoxic substances and bacterial metabolites, as well as secondary bile acids.
  • The production of butyric acid strengthens intestinal epithelial regeneration.
  • They participate in mineral absorption.
  • They promote local immunity and mucin production (which lines the intestinal mucosa).

What is the usefulness of prebiotics?

Prebiotics are a type of dietary fiber that stimulates the growth of probiotics and other bacteria that reside in our bodies.

- Osmotic effect

Prebiotics, like other poorly digestible carbohydrates, exert an osmotic effect on the gastrointestinal tract when they are not fermented; when they are fermented by endogenous flora (i.e., where they exhibit their prebiotic effect), they also increase the production of intestinal gases.

- Bifidogenic or prebiotic effects

These prebiotic or bifidogenic effects depend on the type and concentration of the prebiotic, as well as the concentration of bifidobacteria in the host's intestine.

- Key characteristics

Carbohydrates that meet the criteria of being non-digestible and fermentable by the intestinal flora include inulin, oligofructose, galactooligosaccharides (GOS), or lactulose.

Types of prebiotics

Among foods rich in prebiotics, the most recommended are those with high concentrations of fiber, resistant starch, inulin, and oligosaccharides. Prebiotics are typically found in plant-based foods and also in breast milk.

• Fructans

These are a group of natural oligosaccharides and fructooligosaccharides (FOS). Inulin-type fructans are the best-documented oligosaccharides for their effect on intestinal bifidobacteria and are considered important prebiotic substrates.

- Where to find them

They are found in small amounts in onions, bananas, wheat, artichokes, garlic, and other whole foods.

They can also be extracted from chicory (inulin) or produced from sucrose for use in the food industry.

- Differences

Although related, fructans differ in their origin, structure, and fermentation characteristics, factors that contribute to large variations in measurable colony-forming units, levels of short-chain fatty acids and enzymes, and other outcome measurements.

• Resistant starch

Resistant starch has been the subject of numerous studies documenting its prebiotic effect, both as a standalone ingredient and in combination with FOS.

- Where to find it

Resistant starch is found in raw potatoes, cooked and cooled starchy products (retrograded starch), and immature fruits like bananas, as well as being specifically manufactured for use in the food industry.

- How much to take

The standard dosage for resistant starch is about 20g/day, but low doses ranging from 2.5 to 5g/day have shown a prebiotic effect; the difference in dosage is due to the different fermentation profiles of prebiotic ingredients.

Uses of prebiotics for gut health

In summary, according to the following table (taken and translated from Ross Watson, 2016), we can observe some uses of prebiotics for gut health.



Possible Action


Lactulose, fructooligosaccharides, galactooligosaccharides

Osmotic effect and modulation of endogenous microflora

Irregular Bowel Syndrome (IBS)

Inulin, fructooligosaccharides, galactooligosaccharides

Regulation of individual immune response and pathogenic bacteria

Prevention of Gallstones

Oligosaccharides (fructooligosaccharides, isomaltooligosaccharides, galactooligosaccharides, palatinose, raffinose, and soy oligosaccharides)

Stimulation of bifidobacteria growth in vitro and in vivo

Prevention of Intestinal Infections


Contribution to increased infection resistance. Most Bifidobacterium species have a "sweeping" function

Use of prebiotics in cosmetics

The skin, like our intestines, is colonized by an autonomous microbiota, called the cutaneous microbiome.

• Cutaneous microbiome

This skin microbiome is a result of colonization by various microorganisms, the majority of which are commensal, as they are harmless and even beneficial for the skin.

It is estimated that our skin harbors approximately one billion microbes per square centimeter. Additionally, this microbiome is a distinctive signal as the composition of skin microbes varies from one individual to another.

This collection of microorganisms, along with cutaneous structures and the associated immune system, acts as a protective barrier.

• Skin protective barrier

Sweat glands, hair follicles, and sebaceous glands produce sebum, which helps create a "acid mantle," a protective barrier with a pH of approximately 5 that promotes the development of the microbiome while limiting the entry or colonization of non-beneficial microbes on the skin.

Any change in this microenvironment (whether due to moisture, age, temperature, environmental factors, etc.) can affect skin well-being.

Effect of prebiotics on the skin

As mentioned earlier, prebiotics, when chosen correctly, can "feed" the skin microbiota while not feeding non-beneficial microorganisms, thereby improving skin well-being.

For example, prebiotics like glycerin will feed Cutibacterium acnes, but not sucrose.

• Galactooligosaccharides (GOS)

Galactooligosaccharides (GOS) are considered suitable prebiotics to selectively stimulate the growth of one or a limited number of bacterial species that have the potential to improve skin well-being.

In fact, data extracted from an analysis of clinical studies1 on Atopic Dermatitis in children (AD) using a combination of galactooligosaccharide and fructooligosaccharide showed a 32% reduction in incidence.

• Infant skin

Similarly, infants at risk for atopy who were fed a formula supplemented with prebiotics during their first 6 months of life had a significantly lower cumulative incidence of AD by age 5.1