Key Points:

– Gut microbiota is the term used for describing the composition of microorganisms present in the gut. They include different types of microorganisms ranging from bacterial, to viral, to fungal species.

– A healthy gut comprises a set of gut microorganisms (and gut microbiota) that is largely beneficial to our health and in the meantime minimizing the species that are detrimental to us.

– Our innate set of gut microbiota is thought to be the most suitable and optimum for oneself. This optimum composition deteriorates due to several factors, leading to poorer gut health which may lead to negative health effects.

– The gut microbiota is important due to its multiple functions, including the absorption of nutrients, supporting neurological functions, and influencing metabolic processes.

Introduction To The Gut Microbiota

The human digestive system is simple yet complex at the same time. It harbors communities of microorganisms, some of which are beneficial while others are not. Many factors contribute to the establishment of these bacteria in the gut. The food we eat is one major contributor. According to a study, about 60 tons (60,000 kg) of food passes through the gastrointestinal (GI) tract in an average lifespan [1]. An abundance of microorganisms and substrates are carried along with the food and other digested materials. These foreign microorganisms, along with the innate microorganisms found in our gut, make up the gut microbiota.

What Is The Gut Microbiota?

Biota is coined from the Latin word biote, meaning ‘life’. Gut microbiota is the term used for describing the composition of microorganisms present in the gut. They include different types of microorganisms ranging from bacterial, to viral, to fungal species, which form symbiotic relationships with the host. Studies have shown that there are 10¹⁴ of these microorganisms present in the GI tract, making it approximately ten times more than the number of human cells in the body [2]. Due to these symbiotic relationships between the microorganisms and the human cells, the human body is considered a superorganism.

What Constitutes Gut Health and Why It Is Important

A healthy gut comprises a set of gut microorganisms (and gut microbiota) that is largely beneficial to our health (e.g., Lactobacillus and Bifidobacterium spp.), and in the meantime minimizing the species that are detrimental to us [3]. Our innate set of gut microbiota is thought to be the most suitable and optimum for oneself and it starts developing as early as when the fetus is in the mother’s womb [4]. This optimum composition deteriorates as we age. Along with poorer modern-day diets lacking in prebiotics (i.e., food for the beneficial gut bacteria) as well as increased use of medications such as antibiotics, the composition and amount of good gut bacteria decrease even faster.

This would lead to poorer gut health which may lead to negative effects such as constipation, unhealthy blood pressure [5], sugar [6] and cholesterol levels [7], as well as poor cardiovascular [8], respiratory [9] and immune health [10].

4 Functions Of the Gut Microbiota

The gut microbiota has many functions in the human body, ranging from those related to the gastrointestinal system to metabolism. These roles and functions include aiding in the absorption of nutrients, controlling the population of pathogens, supporting neurological functions and influencing key metabolic processes. Here are 4 key functions of the gut microbiota:

1. Absorption of nutrients

The gut microbiota helps in the fermentation of food molecules such as prebiotic and production of some vitamins like vitamin B and K. It also influences the metabolism of nutrients due to its interactions with the epithelial receptors along the GI lining [11].

2. Controlling population of pathogens

The competitive-exclusion effect of the gut microbiome is one of the many ways it limits the growth of pathogens in the gut. The gut microbiota competes with these foreign microorganisms for nutrients and at the same time, it secretes antimicrobial compounds such as bacteriocins, which prevent the foreign microorganisms from flourishing and harming the host [11].

3. Supporting neurological functions

The digestive tract and the brain communicate with each other through a connection known as the gut-brain axis. Messages in the forms of hormonal, immunological, and neural signals travel back and forth between the central nervous system and the gut via this axis. This enables the brain to control certain GI functions such as movement of food through the digestive tract and the release of digestive enzymes. The gut microbiota produces substances such as short-chain fatty acids (SCFAs) and neurotransmitters that may affect these transmissions [11].

4. Influencing key metabolic processes

The gut microbiota can influence key metabolic processes such as insulin sensitivity, glucose tolerance, fat storage, and appetite, mainly through the regulation of gut hormones release [12].

Related Articles

Gut-Brain-Immune Axis: An Introduction

Gut Microbiota and Its Implications in Diabetes and Blood Sugar

References

1. Bengmark S. Ecological control of the gastrointestinal tract. The role of probiotic flora. Gut. 1998;42(1):2-7.
2. Gill SR, Pop M, Deboy RT, et al. Metagenomic analysis of the human distal gut microbiome. Science. 2006;312(5778):1355-1359.
3. Zhang YJ, Li S, Gan RY, et al. Impacts of gut bacteria on human health and diseases. Int J Mol Sci. 2015 Apr 2;16(4):7493-519.
4. Tanaka M, Nakayama J. Development of the gut microbiota in infancy and its impact on health in later life. Allergol Int. 2017 Oct;66(4):515-522.
5. Yang T, Santisteban MM, Rodriguez V, et al. Gut dysbiosis is linked to hypertension. Hypertension. 2015 Jun;65(6):1331-40.
6. Larsen N, Vogensen FK, van den Berg FW, et al. Gut microbiota in human adults with type 2 diabetes differs from non-diabetic adults. PLoS One. 2010;5(2):e9085.
7. Kriaa A, Bourgin M, Potiron A, et al. Microbial impact on cholesterol and bile acid metabolism: current status and future prospects. J Lipid Res. 2019 Feb;60(2):323-332.
8. Tang WH, Kitai T, Hazen SL. Gut Microbiota in Cardiovascular Health and Disease. Circ Res. 2017 Mar 31;120(7):1183-1196.
9. Enaud R, Prevel R, Ciarlo E, et al. The Gut-Lung Axis in Health and Respiratory Diseases: A Place for Inter-Organ and Inter-Kingdom Crosstalks. Front Cell Infect Microbiol. 2020 Feb 19;10:9.
10. Wu HJ, Wu E. The role of gut microbiota in immune homeostasis and autoimmunity. Gut Microbes. 2012 Jan-Feb;3(1):4-14.
11. Jandhyala SM, Talukdar R, Subramanyam C, et al. Role of the normal gut microbiota. World J Gastroenterol. 2015;21(29):8787-8803.
12. Martin AM, Sun EW, Rogers GB, Keating DJ. The Influence of the Gut Microbiome on Host Metabolism Through the Regulation of Gut Hormone Release. Front Physiol. 2019;10:428.

Share this article: