Inside the human digestive system lives a vast ecosystem of microorganisms known as the gut microbiome. This community is made up of trillions of bacteria, fungi and other microbes that live primarily in the large intestine.
Although the idea of bacteria living in the body may sound surprising, these microbes play an essential role in many aspects of health. The gut microbiome helps break down certain foods, supports the immune system and produces compounds that influence many biological processes throughout the body.
Scientists now recognise the gut microbiome as one of the most important systems influencing digestion, metabolism, inflammation and immune balance. Understanding how these microbes work helps explain why microbiome health is becoming an increasingly important area of scientific research.
Founder Insight
Hanna Sillitoe first became interested in the role of the gut microbiome while naturally treating her psoriasis. During this time she began exploring research into how gut bacteria influence inflammation, digestion and immune responses.
This experience sparked a long-standing interest in how supporting the microbiome may influence overall wellbeing from within.
What Is the Gut Microbiome?
The gut microbiome refers to the collection of microorganisms that live inside the digestive tract.
These microbes include:
- bacteria
- fungi
- viruses
- other microscopic organisms
The majority of these microbes live in the large intestine, where they interact with food particles, immune cells and the lining of the digestive tract.
Scientists estimate that the human body contains trillions of microbial cells, forming a complex ecosystem that plays a crucial role in maintaining balance within the body.
Rather than simply existing within the gut, these microorganisms actively interact with many systems in the body and contribute to essential biological processes.
What Do Gut Bacteria Do?
The gut microbiome performs many important functions that support human health.
Breaking Down Food
Certain foods — particularly dietary fibre — cannot be fully digested by human enzymes. Instead, gut bacteria help break down these substances through a process called fermentation.
During fermentation, microbes convert fibre into beneficial compounds known as short-chain fatty acids, which support the gut lining and help maintain digestive balance.
Supporting the Immune System
A large proportion of the body’s immune cells are located within the digestive system.
Gut microbes interact closely with these immune cells and help regulate immune responses. This interaction plays an important role in maintaining immune balance and supporting the body's ability to respond to potential threats.
Producing Important Compounds
Gut bacteria produce a variety of compounds that influence many systems throughout the body. These include:
- short-chain fatty acids
- certain vitamins such as vitamin K and some B vitamins
- signalling molecules that influence metabolic processes
These microbial metabolites help support gut health and influence communication between different systems within the body.
Influencing Whole-Body Health
Because the microbiome interacts with the immune system, nervous system and metabolic pathways, researchers are exploring how gut bacteria may influence many aspects of health, including digestion, skin health, hormone balance and inflammation.
This network of interactions highlights how the gut microbiome functions as a key regulator of many biological processes.
What Is Microbiome Diversity?
One important concept in microbiome science is microbial diversity.
A healthy microbiome typically contains a wide variety of different bacterial species living in balance within the digestive system.
Greater microbial diversity is often associated with a more resilient and stable gut ecosystem. Diet, lifestyle habits and environmental factors can all influence the diversity of microbes living in the gut.
Researchers continue to study how microbiome diversity may influence digestive health and overall wellbeing.
What Research Shows
Scientific research into the microbiome has expanded rapidly over the past two decades.
Key findings include:
• Trillions of microbes live in the human gut – Studies estimate that the digestive system contains vast numbers of microbial cells forming a complex ecosystem.
• Microbes support digestion and metabolism – Gut bacteria help ferment fibre and produce beneficial compounds that support gut health.
• The microbiome interacts with the immune system – Because many immune cells are located in the digestive tract, microbes play a key role in immune regulation.
• Microbiome diversity is associated with gut resilience – A diverse microbiome may contribute to stability within the digestive ecosystem.
These discoveries have transformed scientific understanding of the microbiome and its role in human health.
Sources
Sender R et al. Revised estimates for the number of human and bacterial cells in the body. PNAS, 2016.
Flint HJ et al. Links between diet, gut microbiota composition and gut metabolism. Proceedings of the Nutrition Society, 2012.
Koh A et al. From dietary fibre to host physiology: short-chain fatty acids as key bacterial metabolites. Cell, 2016.
Gill SR et al. Metagenomic analysis of the human distal gut microbiome. Science, 2006.
Supporting the Gut Microbiome
Maintaining a healthy microbiome may help support digestion, immune balance and overall wellbeing.
Several everyday habits may help support microbial diversity.
Eat a diverse range of plant foods
Plant diversity provides fibre and nutrients that help nourish beneficial gut bacteria.
Increase fibre intake
Fibre acts as fuel for microbes in the digestive system and supports fermentation processes.
Include fermented foods
Fermented foods such as kimchi, sauerkraut and kefir contain naturally occurring microorganisms that may help support microbiome diversity.
Maintain healthy lifestyle habits
Sleep, stress management and physical activity can influence microbiome balance.
Consider probiotic support
Some people choose to support their microbiome with probiotics — live microorganisms designed to help maintain microbial balance within the digestive system.
Common Questions About the Gut Microbiome
How many bacteria live in the gut?
Scientists estimate that the human digestive system contains trillions of microorganisms forming the gut microbiome.
Why is the microbiome important?
The microbiome helps break down food, supports immune regulation and produces compounds that influence many biological processes.
Can diet affect the microbiome?
Yes. Diet is one of the most important factors influencing the composition and diversity of gut bacteria.
Conclusion
The gut microbiome is a complex ecosystem made up of trillions of microorganisms living within the digestive tract. These microbes play an essential role in digestion, immune regulation and metabolic processes throughout the body.
Scientific understanding of the microbiome continues to evolve, but research increasingly highlights the importance of maintaining a diverse and balanced microbial ecosystem.
Supporting gut health through diet, lifestyle habits and microbiome support may help maintain balance within the systems that influence overall wellbeing.
Some people choose to support their microbiome with probiotics — live cultures designed to help maintain a healthy balance of gut bacteria. Learn more about our Multi-Strain Biotic and how it supports gut health.