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Prebiotic: Gut Microbiota, Gut Health, and Beyond


There has been an increasing understanding and awareness of prebiotic, as people are starting to look for diets and foods that are linked with health benefits. There may be a general understanding of what a ‘prebiotic’ is: loosely thought of as the ‘food for the probiotics’. However, many do not know what exactly it is, how is it considered and classified as a prebiotic, what are the types of food that contains it, or the health benefits it can provide.

Other than prebiotics, there is also increasing awareness of the importance of gut health and its effects on other parts of the body, such as the brain, nervous system, and the immune system. How can prebiotics help in improving our gut health? Does it have any effect on our innate and unique set of gut microbiota? How does it complement with the more commonly known probiotics?

Read on to find out more about prebiotics and understand why there is an increasing awareness to them.

What is the innate gut microbiota?

To better understand prebiotics and its functions, we need to first look at what is the gut microbiota (also called gut microbiome in certain literature). The gut microbiota consists of different types of microorganisms such as bacteria, virus, and fungi, and the number of bacterial cells is estimated to outnumber our human cells by about 10 times [1]. Everyone has a unique set of innate (inborn, natural) gut microbiota, due to the differences in many factors that can affect the composition of the microbes, such as the use of antibiotics, environmental, lifestyle and diet factors [2].

This innate gut microbiota is supposedly thought to be the best that nature has offered us, and various factors such as use of antibiotics and natural aging lead to the decrease in the composition and amount of beneficial gut bacteria, which ultimately negatively affects the gut health.

The gut microbiota does not affect just the gut health but is also involved in the health of many other body systems. Firstly, the gut microbiota has effects on our mental health [3], and it is thought to be affected via the gut-brain axis [4]. It may also affect cardiovascular health, including coronary artery disease and heart failure [5]. The gut microbiota can also affect our immune system and inflammation pathways [6]. Other benefits include supporting our blood sugar [7], blood pressure [8], cholesterol levels [9] and respiratory health [10]. This goes to show that the health of our gut microbiota is deeply associated with our general health and well-being.

There is a need to maintain this healthy level of innate gut microbiota for it to contribute to our overall health and well-being. How do we ensure that we have a healthy composition, level, and diversity of gut microbiota? This is where prebiotics come into play.

What is considered a prebiotic?

First on foremost, to understand prebiotic, we need to look at its official definition from international bodies and organization. Prebiotics are not just simply food for the gut microbiota.

According to the International Scientific Association for Probiotics and Prebiotics (ISAPP), a non-profit organization promoting the science of prebiotic and probiotic, a prebiotic is defined as: a substrate that is selectively utilized by host microorganisms conferring a health benefit [11]. The host microorganism here may refer to 2 things: (1) your innate gut microbiota as discussed in the section above, and (2) external supplementation in the form of probiotics.

Other than being simply ‘food’ for these microorganisms, it also must confer ‘health benefits’ for a certain product to be classified as a prebiotic. By doing so, prebiotics encourage the healthy balance of your unique set of resident gut microbiota, creating an environment where the beneficial bacteria (such as Lactobacillus and Bifidobacterium) flourish and crowd out unwanted and harmful bacteria.

The ISAPP has also noted that prebiotics are not the only substance that can affect the microbiota [11]. To qualify as a prebiotic, it must not only simply affect the microbiota, but it should also have selective effects on beneficial species like Bifidobacterium. A prebiotic also needs have adequate evidence to show health benefits for the host, in this case humans [11].

Prebiotic: How it enhances your innate gut microbiota

Prebiotics serve as a form of fuel for the gut microbiota. They are usually not digested and absorbed by the body and reaches the colon largely unchanged. The healthy gut microbiota then ferments the prebiotics. These fermentation process induces the proliferation of healthy gut bacterial species such as Lactobacillus and Bifidobacterium[12].

The fermentation process also produces metabolites such as short-chain fatty acids (SCFAs). These SCFAs and other metabolites are involved in several biological process that confer health benefits to the host, such as glucose and lipid metabolism, immune function and regulating satiety [13].

By taking sufficient prebiotics, we would be able to maintain the level of our innate and beneficial gut bacteria (which is supposedly the most optimum set given to us by nature).

Prebiotic: How it enhances probiotic supplements

There are also benefits for those that are taking external probiotics supplements. Other than enhancing and supporting the growth of your healthy gut microbiota, prebiotics can also aid in maximizing the effects of your probiotic supplements. According to ISAPP, probiotics are defined as: live microorganisms that, when administered in adequate amounts, confer a health benefit on the host [14]. The similar concept of conferring a health benefit applies. By taking prebiotics together with your probiotics, you may help to improve the viability and survival chances of the probiotics that you are taking [15].

Types and Sources of Prebiotics

Not all fibers are prebiotics, but most prebiotics may be classified as dietary fibers [16]. The word ‘prebiotic’ is not used frequently on food labels. Instead, look for the following words to identify the different types of prebiotics:

  • Dextrin, including resistant maltodextrin
  • Inulin
  • Galacto-oligosaccharides (GOS)
  • Fructo-oligosaccharides (FOS)

The following are sources of prebiotic:

  • Health supplements
  • Wholegrains
  • Beans and legumes
  • Onions
  • Garlic
  • Artichokes


Recent research has shown that prebiotic plays an increasingly important role in the gut health by feeding and enhancing the healthy gut microbiota. This in turn leads to optimum health of the various body systems, including your cardiovascular, respiratory, immune, and nervous systems, as well as improvement in markers such as blood sugar, blood pressure, and cholesterol levels.


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