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The gut microbiome is
a measurable biological system

The gut microbiome is a dynamic biological system that is essential to normal human physiology, influencing immune regulation, gut barrier integrity, metabolism, and systemic signaling.1
It is a clinically relevant biological system with meaningful implications for complex and multi-system presentations.

Bacteria

Archaea

Viruses

Fungi

Microbial interactions are shaped by balance, not fixed labels

The nature of these interactions is not fixed, it depends on the gut environment and overall ecological balance. These interactions generally fall into four categories:

COMMENSAL

Present without measurable benefit or harm to the host.

MUTUALISTIC

Contributes positively to metabolism, immune regulation or barrier integrity.

OPPORTUNISTIC

Typically neutral, but may cause harm when ecological balance shifts.

PATHOGENIC

Capable of causing disease or disrupting normal function.

Microbes convert fuel into compounds that influence health

Gut microbes feed on available substrates including dietary fibre, proteins and host-derived compounds and convert them into metabolites that interact with body systems.^1,2What they produce depends on which microbes are present, the functional pathways they carry, and the fuel sources available to them.

001

Metabolism

Microbial metabolites influence energy use, lipid processing and systemic metabolic balance

002

Immune regulation

The gut microbiome helps regulate immune responses and maintain immune balance

003

Gut barrier function

Microbial activity supports epithelial integrity

004

Gut–brain & systemic signalling

Microbial activity supports epithelial integrity

The microbiome functions as part of human biology — not separate from it.

It’s not enough to know which microbes are present, you need to know what the ecosystem is doing

Microbiome species vary widely between individuals, yet different species can produce the same essential metabolites. Two people with very different microbial profiles may share comparable functional output.^4-6
This is why clinical insight increasingly focuses on metabolic activity, such as butyrate production, rather than species detection alone..

Microbiome insight adds a systems-level lens to clinical care.

The microbiome interacts with multiple biological systems simultaneously, it can provide additional interpretive insight in chronic and complex cases.
In multi-system presentations not fully explained by traditional markers, understanding microbial function adds a broader systems-level perspective.

In multi-system presentations not fully explained by traditional markers, understanding microbial function adds a broader systems-level perspective.

In multi-system presentations not fully explained by traditional markers, understanding microbial function adds a broader systems-level perspective.

Ecological balance

A healthy microbiome is not defined by the presence of specific organisms, but by the balance and diversity of the community as a whole. Disruptions to this balance can shift microbial interactions from beneficial to opportunistic.

Functional pathways

Two individuals may have very different microbial species yet share similar functional outputs - such as butyrate production or mucin degradation. Assessing what microbes are doing metabolically often provides more meaningful insight than species detection alone.

Metabolic output

Microbial metabolites interact with body tissues, influencing immune regulation, barrier integrity, metabolism and systemic signalling. What is produced depends on the microbes present, the functional pathways they carry, and the fuel sources available  to them.

Patient context

The same microbial profile can produce different clinical effects depending on individual factors. Many factors including diet, medication use, immune function, and gut barrier integrity can  all shape how the microbiome behaves and what it means for  that patient.

Key Takeaway

The human microbiome is a measurable biological system that functions as part of normal human physiology.

Community-wide measures such as diversity and functional output can be more clinically meaningful than detection of specific species.
As understanding of the microbiome grows, it is becoming an increasingly valuable part of clinical assessment, especially in chronic or multi-system presentations.

Explore the complete article

Read the full guide to microbiome structure, function and clinical interpretation.

Full article

References:

Sender R. Fuchs S. & Milo R. Revised Estimates for the Number of Human and Bacteria Cells in the Body.PLoSBiology 14 e1002533 (2016).
HuttenhowerC. et al. Structure function and diversity of the healthy human microbiome. Nature 486 207–214 (2012).
Jiang Y. Che L. & Li S. C. Deciphering the personalized functional redundancy hierarchy in the gut microbiome. Microbiome 14 17 (2025).
Fan Y. & Pedersen O. Gut microbiota in human metabolic health and disease. Nat. Rev.Microbiol. 19 55–71 (2021).
Lynch S. V. & Pedersen O. The human intestinal microbiome in health and disease. N. Engl. J. Med. 375 2369–2379 (2016).
Koh A. DeVadderF. Kovatcheva-Datchary P. & Bäckhed F. From Dietary Fiber to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites. Cell 165 1332–1345 (2016).
ZhernakovaA. et al. Population-based metagenomics analysis reveals markers for gut microbiome composition and diversity. Science 352 565–569 (2016).
De Filippis F. et al. Distinct genetic and functional traits of human intestinalPrevotellacopri strains are associated with different habitual diets. Cell Host Microbe 25 444–453 (2019).
Zhang Z. J. et al.Comprehensive analyses of a large human gutBacteroidales culture collection reveal species- and strain-level diversity and evolution. Cell Host Microbe 32 1853–1867 (2024).
Tian L. et al. Deciphering functional redundancy in the human microbiome. Nat Commun 11 6217 (2020).
denBestenG. et al. The role of short-chain fatty acids in the interplay between diet gut microbiota and host energy metabolism. Journal of Lipid Research 54 2325–2340 (2013).
Morrison D. J. & Preston T. Formation of short chain fatty acids by the gut microbiota and their impact on human metabolism. Gut Microbes 7 189–200 (2016).
Venkatesh M. et al. Symbiotic Bacterial Metabolites Regulate Gastrointestinal Barrier Function via the Xenobiotic Sensor PXR and Toll-like Receptor 4. Immunity 41 296–310 (2014).
Honda K. & Littman D. R. The microbiota in adaptive immune homeostasis and disease. Nature 535 75–84 (2016).
Furusawa Y. et al. Commensal microbe-derived butyrate induces the differentiation of colonic regulatory T cells. Nature 504 446–450 (2013).
Arpaia N. et al. Metabolites produced by commensal bacteria promote peripheral regulatory T-cell generation. Nature 504 451 (2013).
MukhopadhyaI. & Louis P. Gut microbiota-derived short-chain fatty acids and their role in human health and disease. Nat Rev Microbiol 23 635–651 (2025).
Singh V. et al. Butyrate producers “The Sentinel of Gut”: Their intestinal significance with and beyond butyrate and prospective use as microbial therapeutics. Front.Microbiol. 13 (2023).
Ren T. et al. Indole Propionic Acid Regulates Gut Immunity: Mechanisms of Metabolite-Driven Immunomodulation and Barrier Integrity. JMicrobiolBiotechnol 35 e2503045 (2025).
Cryan J. F. et al. The Microbiota-Gut-Brain Axis. Physiological Reviews 99 1877–2013 (2019).
Matsuura M. Structural Modifications of Bacterial Lipopolysaccharide that Facilitate Gram-Negative Bacteria Evasion of Host Innate Immunity. Front. Immunol. 4 (2013).
ZamyatinaA. & Heine H. Lipopolysaccharide Recognition in the Crossroads of TLR4 and Caspase-4/11 Mediated Inflammatory Pathways. Front. Immunol. 11 (2020).
Zhu M. et al. C-reactive protein and cancer risk: a pan-cancer study. BMC Med 20 301 (2022).
RidkerP. M. et al. Relationship of C-reactive protein reduction to cardiovascular event reduction following treatment with canakinumab. The Lancet 391 319–328 (2018).
Pradhan A. D. Manson J. E. Rifai N. Buring J. E. &RidkerP. M. C-Reactive Protein Interleukin 6 and Risk of Developing Type 2 Diabetes Mellitus. JAMA 286 327–334 (2001).
d’HennezelE. Abubucker S. Murphy L. O. & Cullen T. W. Total Lipopolysaccharide from the Human Gut Microbiome Silences Toll-Like Receptor Signaling. mSystems 2 e00046-17 (2017).
Khorsand B. et al. Overrepresentation of Enterobacteriaceae and Escherichia coli is the major gut microbiome signature in Crohn’s disease and ulcerative colitis. Front. Cell. Infect.Microbiol. 12 (2022).
Thompson K. N. et al. Alterations in the gut microbiome implicate key taxa and metabolic pathways across inflammatory arthritis phenotypes. Science Translational Medicine 15 eabn4722 (2023).
Desai M. S. et al. A Dietary Fiber-Deprived Gut Microbiota Degrades the Colonic Mucus Barrier and Enhances Pathogen Susceptibility. Cell 167 1339-1353.e21 (2016).
Zheng J. et al.Noninvasivemicrobiome-based diagnosis of inflammatory bowel disease. Nat Med 30 3555–3567 (2024).
Qin J. et al. A metagenome-wide association study of gut microbiota in type 2 diabetes. Nature 490 55 (2012).
Tuomainen M. et al. Associations of serumindolepropionicacid a gut microbiota metabolite with type 2 diabetes and low-grade inflammation in high-risk individuals. Nutrition & Diabetes 8 35 (2018).
Peron G. et al. A Polyphenol-Rich Diet Increases the Gut Microbiota Metabolite Indole 3-Propionic Acid in Older Adults with Preserved Kidney Function. Molecular Nutrition & Food Research 66 2100349 (2022).
SpraggeF. et al. Microbiome diversity protects against pathogens by nutrient blocking. Science 382 eadj3502 (2023).
ByndlossM. X. et al. Microbiota-activated PPAR-γ signaling inhibits dysbiotic Enterobacteriaceae expansion. Science 357 570–575 (2017).

The gut microbiome is
a measurable biological system

The gut microbiome is fundamental to normal human physiology. It is a dynamic ecosystem that influences immune regulation, gut barrier integrity, metabolism, and systemic signalling.⁴

This is a two-way relationship. The microbiome contributes to metabolic activity, produces bioactive compounds, and participates in immune signalling.

In turn, the body provides nutrients that support gut microbes  and influences how they behave. Diet, immune activity, and gut conditions all shape which microbes thrive and what they do.^4,5

The microbiome is an clinically relevant biological system with meaningful implications for complex and multi-system presentations. Clinically, this is especially important for patients whose symptoms don’t fit neatly into a single diagnosis or one clear cause.

Bacteria

Archaea

Viruses

Fungi

The role of gut microbes depends on ecological context

The role a microbe plays is not fixed, it depends on the gut environment and the overall ecological balance of the community. Host-microbe interactions generally fall into four broad categories:

COMMENSAL

Present without measurable benefit or harm to the host.

MUTUALISTIC

Contributes positively to metabolism, immune regulation or barrier integrity.

OPPORTUNISTIC

Typically neutral, but may cause harm when ecological balance shifts.

PATHOGENIC

Capable of causing disease or disrupting normal function.

Microbes convert fuel into compounds that influence health

Gut microbes feed on available substrates, including dietary fibre, proteins, and host-derived compounds, and convert them into metabolites that interact with body systems.^4,6
Some of these metabolites act locally within the gut, influencing barrier integrity and immune signalling. Others enter the bloodstream and affect organs and processes throughout the body.

What is produced depends on:

Species: The microbes present

Functional pathways: The key metabolic functions they perform

Dominant substrates: The main fuel sources they utilise

Gut environment: Conditions present in the gut such as pH, oxygen  availability, and nutrient availability.

This is why microbiome assessment increasingly focuses on functional capacity and metabolic output — not just species detection.

It’s not enough to know which microbes are present you need to know what the ecosystem is doing

Microbiome composition varies significantly between individuals.⁷ While certain microbial groups are commonly found across populations, the relative abundance, diversity, and functional output differ from person to person.

Function matters more than labels

Microbiome composition varies significantly between individuals.⁷ This variability is shaped by many factors, including diet, medication use, genetics, environmental exposures, and lifestyle,  all of which influence both microbial composition and metabolic capacity.⁷

Two individuals can share similar broad microbial groups yet differ considerably in their specific species or strains,² and those species and strains may carry different genes with different metabolic capacities.8,9 The reverse is also true: two people with very different microbial profiles may share comparable functional outputs, because different species can produce the same metabolites.^2,3,10

Key helpful functions of the gut microbiome

The gut microbiome influences health not by controlling organs directly, but through the metabolites it produces and the signals they generate.
While the microbiome’s influence on the body is broad, four well-characterised areas are particularly relevant to clinical practice: metabolism, immune regulation, gut barrier integrity, and systemic signalling. Importantly, this relationship is bidirectional – the body’s environment, including diet, immune activity, and gut conditions, also shapes the microbiome^.4,5

Metabolism

Gut microbes act like a metabolic organ, producing thousands of different metabolites from dietary and host-derived compounds.^11,12 Some of these metabolites stay in the gut, where they can affect inflammation, transit time, and the gut lining.
Others cross into the bloodstream and can influence inflammation, energy balance, lipid processing, and metabolic regulation throughout the body.^11,12

Immune regulation

The microbiome continuously interacts with immune cells within the gut-associated lymphoid tissue (GALT).14 Microbial antigens and metabolites help calibrate immune responsiveness – supporting tolerance to harmless signals while maintaining the ability to respond to genuine threats. For example, some short-chain fatty acids promote the production of regulatory T cells that help prevent over-reactive inflammation.^15,16 Rather than simply stimulating immunity, the microbiome plays a central role in immune homeostasis.¹⁴

Gut barrier function

The gut barrier is a set of layers that separates gut contents from the bloodstream: a mucus layer, a single layer of epithelial cells, and tight junctions between those cells. Microbial metabolites — including butyrate and some tryptophan-derived indoles – can strengthen this barrier by providing an energy source to gut cells and promoting tight junction integrity.^6,13,17,19
Thus, barrier function is not purely structural — it is actively maintained by microbial metabolism.

Systemic signalling

Microbial metabolites interact with the body’s receptors and influence signalling pathways beyond the gut, including enteroendocrine signalling, neural circuits, and immune pathways.^4,20The gut and brain communicate through nerves (including the vagus nerve), hormones, and immune signals. Gut microbes can influence these pathways by producing or modifying neuroactive compounds and by modulating inflammation levels.²⁰

The microbiome functions as part of human biology — not separate from it.

Diet

Especially fibre intake and overall dietary pattern. A wide range of plant foods provides diverse fibres that can support microbial diversity and short chain fatty acid production.

Medications

Antibiotics, proton pump inhibitors, metformin, and others can all alter microbial composition. Antibiotics in particular can have a significant and sometimes lasting impact on the microbiome.

Infections and inflammation

Gut infections and inflammatory conditions can shift the ecological balance of the microbiome, for example, by altering nutrient availability or oxygen levels in the gut, which can favour the expansion of certain organisms over others

Lifestyle and environment

Factors such as sleep, stress, exercise, alcohol, and smoking all have the potential to influence gut function and, in turn, microbial composition.

What happens when the microbiome is out of balance

There is no single "perfect" microbiome. Healthy people can have very different microbial profiles. However, when the balance shifts significantly, it can affect what the microbiome produces and how the body responds. An imbalanced microbiome — sometimes called dysbiosis — often involves one or more of the following:

001

Loss of helpful microbes (for example, fibre-fermenting short-chain fatty acid producers)

002

Overgrowth of potentially harmful microbes (sometimes called pathobionts)

003

Reduced diversity (fewer different types of microbes)

004

A shift in what the microbiome is doing — such as producing fewer protective molecules and more inflammatory molecules

How imbalances can affect the immune system and inflammation

The immune system is one of the most direct ways the gut microbiome can affect whole-body health. When the balance of microbial metabolites shifts, with fewer anti-inflammatory products such as butyrate^15,16and more pro-inflammatory products such as hexa-acylated LPS^21,22 – immune cells may stay activated for prolonged periods, leading to low-grade chronic inflammation. This type of inflammation is linked with many chronic diseases.^23-25

Pro-inflammatory LPS (endotoxin)

Specific types of LPS (hexa-acylated or higher) are  strong triggers for inflammation because they can activate a receptor on immune cells called TLR4, which can initiate an inflammatory cascade.²¹  Other types of LPS are weaker and may even help block this signalling.²⁶ When the balance shifts toward bacteria that produce strongly inflammatory LPS, inflammatory signalling can increase. Increased levels of these bacteria have been observed in Crohn’s disease, rheumatoid arthritis, and ankylosing spondylitis.^27-28

Mucus layer damage when fibre is low

If dietary fibre is limited, some microbes can switch  to using mucus as a fuel source. In animal studies,  a fibre-deprived diet increased mucus-degrading bacteria, thinned the mucus barrier, and increased susceptibility to infection and inflammation.₂₉In humans, the relative abundance of mucin-degrading pathways has been positively correlated with faecal calprotectin, a clinical marker of inflammation in the gut.⁷

Lower butyrate and IPA-producing species

Butyrate is a short-chain fatty acid that serves as the primary energy source for colon cells and plays a key role in immune regulation. Indole-propionic acid (IPA) is a tryptophan-derived metabolite also involved in immune regulation and maintaining intestinal barrier integrity. Reduced levels of butyrate-producing species and plasma IPA have been associated with inflammatory bowel diseases and type 2 diabetes.^30-32

Defending against pathogens

A diverse microbiome with adequate levels of butyrate producers can help prevent overgrowth of harmful microbes by competing for space and nutrients, producing antimicrobial substances, and maintaining key signalling pathways.^34-35When the microbiome is disrupted, for example after antibiotics, this protective function can be compromised, leaving people more susceptible to pathogen infections.

What matters most in clinical interpretation

Because the microbiome interacts with multiple biological systems, it can provide additional interpretive context in chronic and complex presentations -- particularly when traditional markers do not fully explain a patient's symptoms. The microbiome is not best understood through a "good vs. bad bugs" lens. As outlined in the preceding sections, clinical interpretation is more informative when it considers these key factors: the ecological balance of the community, the functional pathways present, the metabolic output of those pathways, and the individual patient's context.

Ecological balance: community stability and diversity

A healthy microbiome is not defined by the presence of specific organisms, but by the balance and diversity of the community as a whole. Disruptions to this balance -- through antibiotics, dietary changes, or infection -- can shift microbial interactions from beneficial to opportunistic.4

Functional pathways: what microbes do, not just which are present

Two individuals may have very different microbial species yet share similar functional capacity, such as the ability to produce butyrate or degrade mucin(2,3,10).
Equally, two similar-looking profiles may differ in what they actually produce. Assessing what the microbiome is capable of doing often provides more clinically meaningful insight than cataloguing which species are present.

Metabolic output: the compounds produced and their effects

Microbial metabolites interact with body tissues, influencing immune regulation, barrier integrity, metabolism and systemic signalling.4 The microbial metabolites produced depends on which microbes are present, the functional pathways they carry, the gut, environment and the fuel sources available to them.

Patient context: immune status, diet, and environment

The same microbial profile can produce different clinical effects depending on individual factors. Many factors including diet,  medication use, immune function, and gut barrier integrity can all shape how the microbiome behaves and what the results may mean for that patient.

Key Takeaway

The gut microbiome is a measurable, modifiable part of human physiology. It functions as an ecosystem — and like any ecosystem, its health depends on the balance, diversity, and functional capacity of the community as a whole, not just the presence or absence of individual organisms.

For clinicians, the most useful insight from the microbiome is often functional rather than taxonomic: what the microbial community is producing, how that interacts with the patient’s immune system, gut barrier, and metabolic regulation, and how those outputs may be shifting in the context of that individual’s diet, medications, and clinical picture.

For clinicians, microbiome insights provide an additional lens for understanding systemic regulation, particularly in chronic and complex symptom patterns.

As our understanding of the microbiome deepens, so does the opportunity to use it as a meaningful part of clinical assessment, particularly for patients with chronic or multi-system presentations where traditional markers tell only part of the story.

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References:

Sender R. Fuchs S. & Milo R. Revised Estimates for the Number of Human and Bacteria Cells in the Body.PLoSBiology 14 e1002533 (2016).
HuttenhowerC. et al. Structure function and diversity of the healthy human microbiome. Nature 486 207–214 (2012).
Jiang Y. Che L. & Li S. C. Deciphering the personalized functional redundancy hierarchy in the gut microbiome. Microbiome 14 17 (2025).
Fan Y. & Pedersen O. Gut microbiota in human metabolic health and disease. Nat. Rev.Microbiol. 19 55–71 (2021).
Lynch S. V. & Pedersen O. The human intestinal microbiome in health and disease. N. Engl. J. Med. 375 2369–2379 (2016).
Koh A. DeVadderF. Kovatcheva-Datchary P. & Bäckhed F. From Dietary Fiber to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites. Cell 165 1332–1345 (2016).
ZhernakovaA. et al. Population-based metagenomics analysis reveals markers for gut microbiome composition and diversity. Science 352 565–569 (2016).
De Filippis F. et al. Distinct genetic and functional traits of human intestinalPrevotellacopri strains are associated with different habitual diets. Cell Host Microbe 25 444–453 (2019).
Zhang Z. J. et al.Comprehensive analyses of a large human gutBacteroidales culture collection reveal species- and strain-level diversity and evolution. Cell Host Microbe 32 1853–1867 (2024).
Tian L. et al. Deciphering functional redundancy in the human microbiome. Nat Commun 11 6217 (2020).
denBestenG. et al. The role of short-chain fatty acids in the interplay between diet gut microbiota and host energy metabolism. Journal of Lipid Research 54 2325–2340 (2013).
Morrison D. J. & Preston T. Formation of short chain fatty acids by the gut microbiota and their impact on human metabolism. Gut Microbes 7 189–200 (2016).
Venkatesh M. et al. Symbiotic Bacterial Metabolites Regulate Gastrointestinal Barrier Function via the Xenobiotic Sensor PXR and Toll-like Receptor 4. Immunity 41 296–310 (2014).
Honda K. & Littman D. R. The microbiota in adaptive immune homeostasis and disease. Nature 535 75–84 (2016).
Furusawa Y. et al. Commensal microbe-derived butyrate induces the differentiation of colonic regulatory T cells. Nature 504 446–450 (2013).
Arpaia N. et al. Metabolites produced by commensal bacteria promote peripheral regulatory T-cell generation. Nature 504 451 (2013).
MukhopadhyaI. & Louis P. Gut microbiota-derived short-chain fatty acids and their role in human health and disease. Nat Rev Microbiol 23 635–651 (2025).
Singh V. et al. Butyrate producers “The Sentinel of Gut”: Their intestinal significance with and beyond butyrate and prospective use as microbial therapeutics. Front.Microbiol. 13 (2023).
Ren T. et al. Indole Propionic Acid Regulates Gut Immunity: Mechanisms of Metabolite-Driven Immunomodulation and Barrier Integrity. JMicrobiolBiotechnol 35 e2503045 (2025).
Cryan J. F. et al. The Microbiota-Gut-Brain Axis. Physiological Reviews 99 1877–2013 (2019).
Matsuura M. Structural Modifications of Bacterial Lipopolysaccharide that Facilitate Gram-Negative Bacteria Evasion of Host Innate Immunity. Front. Immunol. 4 (2013).
ZamyatinaA. & Heine H. Lipopolysaccharide Recognition in the Crossroads of TLR4 and Caspase-4/11 Mediated Inflammatory Pathways. Front. Immunol. 11 (2020).
Zhu M. et al. C-reactive protein and cancer risk: a pan-cancer study. BMC Med 20 301 (2022).
RidkerP. M. et al. Relationship of C-reactive protein reduction to cardiovascular event reduction following treatment with canakinumab. The Lancet 391 319–328 (2018).
Pradhan A. D. Manson J. E. Rifai N. Buring J. E. &RidkerP. M. C-Reactive Protein Interleukin 6 and Risk of Developing Type 2 Diabetes Mellitus. JAMA 286 327–334 (2001).
d’HennezelE. Abubucker S. Murphy L. O. & Cullen T. W. Total Lipopolysaccharide from the Human Gut Microbiome Silences Toll-Like Receptor Signaling. mSystems 2 e00046-17 (2017).
Khorsand B. et al. Overrepresentation of Enterobacteriaceae and Escherichia coli is the major gut microbiome signature in Crohn’s disease and ulcerative colitis. Front. Cell. Infect.Microbiol. 12 (2022).
Thompson K. N. et al. Alterations in the gut microbiome implicate key taxa and metabolic pathways across inflammatory arthritis phenotypes. Science Translational Medicine 15 eabn4722 (2023).
Desai M. S. et al. A Dietary Fiber-Deprived Gut Microbiota Degrades the Colonic Mucus Barrier and Enhances Pathogen Susceptibility. Cell 167 1339-1353.e21 (2016).
Zheng J. et al.Noninvasivemicrobiome-based diagnosis of inflammatory bowel disease. Nat Med 30 3555–3567 (2024).
Qin J. et al. A metagenome-wide association study of gut microbiota in type 2 diabetes. Nature 490 55 (2012).
Tuomainen M. et al. Associations of serumindolepropionicacid a gut microbiota metabolite with type 2 diabetes and low-grade inflammation in high-risk individuals. Nutrition & Diabetes 8 35 (2018).
Peron G. et al. A Polyphenol-Rich Diet Increases the Gut Microbiota Metabolite Indole 3-Propionic Acid in Older Adults with Preserved Kidney Function. Molecular Nutrition & Food Research 66 2100349 (2022).
SpraggeF. et al. Microbiome diversity protects against pathogens by nutrient blocking. Science 382 eadj3502 (2023).
ByndlossM. X. et al. Microbiota-activated PPAR-γ signaling inhibits dysbiotic Enterobacteriaceae expansion. Science 357 570–575 (2017).

Microbiome research is no longer about detection, it’s about function

Over the past two decades, microbiome research has moved from simply identifying which microbes are present to understanding what they do and how they interact with the host.² Large population studies have shown that while microbial species differ widely between individuals, many core metabolic functions are preserved.³

001

EARLY 2000S

Species cataloguing and taxonomic classification

002

2010’s

Functional profiling and metagenomic sequencing

003

current

Clinical integration and longitudinal intervention studies

Advances in metagenomic sequencing now enable functional profiling — assessing microbial gene content and pathway capacity rather than relying on species-level associations alone.³ Longitudinal studies and controlled human interventions continue to clarify how the microbiome responds to diet, medication and environmental exposure.^4,5

Microbial function significantly influences chronic conditions

The gut microbiome can influence chronic disease by affecting core functions such as metabolism, immune regulation, gut barrier integrity, and systemic signalling.¹This helps explain why microbial imbalance may contribute to both gastrointestinal symptoms and wider systemic presentations. ^1,6,7,8

In practice, these disturbances may present as persistent inflammatory symptoms, heightened sensitivity to dietary triggers, altered bowel habits, fatigue, or variable response to established treatments^.1,6,7

Four core physiological functions influenced by the microbiome

The microbiome influences health through measurable host–microbe interactions that affect metabolism, immune regulation, gut barrier integrity, and systemic signalling. Understanding these mechanisms can help clinicians interpret how microbial ecology may contribute to symptom patterns and disease progression.¹

Immune
regulation

Microbial components and metabolites interact continuously with immune cells within the intestinal mucosa. Short-chain fatty acids and other microbial metabolites influence regulatory T-cell activity, cytokine production and immune signalling pathways.⁶

Associated conditions

IBD⁹, type 1 diabetes¹⁰, rheumatoid arthritis¹⁰

Gut barrier
function

Microbial metabolites support epithelial energy metabolism, tight junction stability, and mucosal signalling. When disrupted, increased permeability and altered mucosal signalling may contribute to immune activation and gastrointestinal symptoms.^7,11

Associated conditions

IBS¹², IBD⁹, coeliac disease⁷

Metabolism

Microbial metabolites interact with host receptors involved in glucose and appetite regulation, lipid metabolism and inflammatory signalling pathways. These compounds influence endocrine signalling, energy metabolism and inflammation.⁸

Associated conditions

Obesity, type 2 diabetes, NAFLD¹

Systemic
signalling

Microbial metabolites interact with host receptors and influence signalling pathways beyond the gut, including enteroendocrine signalling, neural circuits, and immune pathways.¹¹

Associated conditions

Cardiovascular disease, Parkinson’s disease, type 2 diabetes^13,14

Simplified microbiome models are not sufficient for effective care

Wellness framing

“Good vs bad bacteria.” Rebalance with a single product.
One-size-fits-all interventions. No consideration of individual ecology or patient context.

Clinical science

Dynamic ecosystems. Functional capacity and ecological structure. Strain-level differences. Context-dependent metabolic effects. Bidirectional microbiome signalling.

Two individuals taking the same probiotic or dietary intervention may experience different outcomes depending on their existing microbial ecology, metabolic pathways and host physiology.¹⁵ Without understanding this context, interventions may fail to address the mechanisms contributing to symptoms or disease progression.

A clinically responsible framework recognises individual variation, strain-level functional differences, context-dependent metabolic effects and bidirectional host–microbe signalling.^2,3,15,16

Key Takeaway

The microbiome is directly involved in physiological functions central to chronic disease, including metabolism, immune regulation, gut barrier integrity, and systemic signalling.¹ It is a biologically active system embedded within human physiology.

Understanding microbial ecosystem function is therefore an important component of modern clinical medicine and interpreting how the microbiome influences human health.¹⁷

Fan Y, Pedersen O. Gut microbiota in human metabolic health and disease. Nat Rev Microbiol. 2021;19(1):55–71. https://doi.org/10.1038/s41579-020-0433-9
Costello EK, Stagaman K, Dethlefsen L, Bohannan BJ, Relman DA. The application of ecological theory toward an understanding of the human microbiome. Science. 2012;336(6086):1255–62.
Human Microbiome Project Consortium. Structure, function and diversity of the healthy human microbiome. Nature. 2012;486(7402):207–14.
Dethlefsen L, Relman DA. Incomplete recovery and individualized responses of the human distal gut microbiota to repeated antibiotic perturbation. Proc Natl Acad Sci USA. 2011;108(Suppl 1):4554–61.
Zhou X, Shen X, Johnson JS, et al. Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease. Cell Host Microbe. 2024;32(4):506–526.e9.
Tan J, McKenzie C, Potamitis M, Thorburn AN, Mackay CR, Macia L. The role of short-chain fatty acids in health and disease. Adv Immunol. 2014;121:91–119.
Ornelas A, Dowdell AS, Lee JS, Colgan SP. Microbial Metabolite Regulation of Epithelial Cell-Cell Interactions and Barrier Function. Cells. 2022;11(6):944.
Koh A, De Vadder F, Kovatcheva-Datchary P, Bäckhed F. From dietary fiber to host physiology: short-chain fatty acids as key bacterial metabolites. Cell. 2016;165(6):1332–1345. https://doi.org/10.1016/j.cell.2016.05.041
Lloyd-Price J, Arze C, Ananthakrishnan AN et al. Multi-omics of the gut microbial ecosystem in inflammatory bowel diseases. Nature. 2019;569(7758):655–662. https://doi.org/10.1038/s41586-019-1237-9
Honda K, Littman DR. The microbiota in adaptive immune homeostasis and disease. Nature. 2016;535(7610):75–84. https://doi.org/10.1038/nature18848
Carabotti M, Scirocco A, Maselli MA, Severi C. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Ann Gastroenterol. 2015;28(2):203–209.
Staudacher HM, Mikocka-Walus A, Ford AC. Common mental disorders in irritable bowel syndrome: pathophysiology, management, and considerations for future randomised controlled trials. Lancet Gastroenterol Hepatol. 2021;6(5):401–410. https://doi.org/10.1016/S2468-1253(20)30363-0
de Vos WM, Tilg H, Van Hul M, Cani PD. Gut microbiome and health: mechanistic insights. Gut. 2022;71(5):1020–1032. https://doi.org/10.1136/gutjnl-2021-326789
Cryan JF, O’Riordan KJ, Cowan CSM, et al. The microbiota-gut-brain axis. Physiol Rev. 2019;99(4):1877–2013. https://doi.org/10.1152/physrev.00018.2018
Leshem A, Segal E, Elinav E. The Gut Microbiome and Individual-Specific Responses to Diet. mSystems. 2020;5(5):e00665-20.
Zmora N, Suez J, Elinav E. You are what you eat: diet, health and the gut microbiota. Nat Rev Gastroenterol Hepatol. 2019;16(1):35–56. https://doi.org/10.1038/s41575-018-0061-2
Lynch SV, Pedersen O. The human intestinal microbiome in health and disease. N Engl J Med. 2016;375(24):2369–2379. https://doi.org/10.1056/NEJMra1600266

When microbial activity influences these systems, it can contribute to symptom persistence, inflammatory burden and variability in treatment response. In practice, clinicians may therefore consider whether host–microbe interactions are influencing a patient’s presentation, particularly in complex or chronic conditions where symptoms cannot be fully explained by structural pathology alone.

Integrated across core disciplines

Immunology

Immune education, inflammatory regulation, mucosal immunity

Gastroenterology

Barrier integrity, mucosal immune responses, motility

Endocrinology

Hormone regulation, appetite signalling, glucose metabolism

Metabolic medicine

Energy metabolism, lipid metabolism, systemic inflammatory tone

Positioning the microbiome within clinical medicine also requires adherence to the evidentiary and regulatory standards that govern medical practice. Clinical claims must be supported by reproducible evidence and remain proportionate to what current data can demonstrate. This is why microbiome research in medical contexts avoids overstating conclusions and remains grounded in established biological mechanisms.

Recognising the microbiome as clinically relevant does not mean attributing disease to microbial imbalance alone. Rather, it represents an additional physiological layer that interacts with systems already central to clinical medicine.

This is where microbiome science becomes clinically relevant. When microbial activity influences these systems, it can contribute to symptom persistence, inflammatory burden and variability in treatment response.

In practice, clinicians may therefore consider whether host–microbe interactions are influencing a patient’s presentation, particularly in complex or chronic conditions where symptoms cannot be fully explained by structural pathology alone.

Microbiome research is no longer about detection, it’s about function

Over the past two decades, microbiome research has moved from simply identifying which microbes are present to understanding what they do and how they interact with the body. Large population studies have shown that while microbial species differ widely between individuals, many core metabolic functions are preserved.^2,3

001

EARLY 2000S

Species cataloguing and taxonomic classification

002

2010’s

Functional profiling and metagenomic sequencing

003

current

Clinical integration and longitudinal intervention studies

Early Microbiome Research

Focused on identifying which microbial species are present
Relied on organism detection and taxonomic classification
Highlighted large species differences between individuals
Limited ability to assess microbial function
Mostly cross-sectional studies describing composition

Current Microbiome Research

Focuses on what microbes do and how they interact with physiology
Examines microbial metabolic activity and functional pathways
Shows core metabolic functions are conserved across populations
Metagenomic sequencing enables functional profiling
Longitudinal studies examine response to diet and medication

Core physiological functions influenced by the microbiome

IMMUNE REGULATION

Microbial components and metabolites interact continuously with immune cells within the intestinal mucosa, including gut-associated lymphoid tissue. Short-chain fatty acids and other microbial metabolites influence regulatory T-cell activity, cytokine production and immune signalling pathways.⁸

HEALTHY FUNCTION

Microbial signals support immune tolerance to dietary antigens and commensal microbes while preventing excessive inflammatory activation.

DYSREGULATION

Persistent inflammatory symptoms, heightened immune sensitivity to dietary triggers, mucosal inflammation, exacerbation of immune-mediated gastrointestinal disorders.

Associated conditions
BD¹⁴, type 1 diabetes¹⁰, rheumatoid arthritis¹⁰

GUT BARRIER FUNCTION

The intestinal epithelium is metabolically active and responsive to microbial signals. Microbial metabolites support epithelial energy metabolism, tight junction stability, and mucosal signalling, helping maintain a stable interface between luminal microbes and host tissues. When this regulation is disrupted, increased permeability and altered mucosal signalling may contribute to immune activation and gastrointestinal symptoms.⁹

HEALTHY FUNCTION

The gut barrier functions as a stable interface between luminal microbes and host tissues, allowing efficient nutrient absorption while limiting inappropriate immune activation.

DYSREGULATION

Increased intestinal permeability, impaired epithelial integrity, and altered mucosal signalling, which may contribute to inappropriate immune activation and gastrointestinal symptoms.

Associated conditions
IBS³, IBD¹⁰, coeliac disease¹⁰

SYSTEMIC SIGNALLING

Microbial metabolites interact with host receptors and influence signalling beyond the gut, including enteroendocrine signalling, neural circuits, and immune pathways. The gut and brain communicate through nerves, hormones, and immune signals. Gut microbes can influence these pathways by producing or modifying neuroactive compounds and by modulating inflammation levels.^11,12

HEALTHY FUNCTION

Coordinated neuroimmune and enteroendocrine signalling, stable gut–brain communication, balanced stress response.

DYSREGULATION

Altered stress response, neuroinflammation, disrupted gut–brain communication, variable systemic signalling.

Associated conditions
Cardiovascular disease, type 2 diabetes, Parkinson’s disease^6,10

METABOLISM

Microbial metabolites interact with host receptors involved in glucose and appetite regulation, lipid metabolism and inflammatory signalling pathways. Short-chain fatty acids and related compounds influence endocrine signalling, energy metabolism and inflammation.¹²

HEALTHY FUNCTION

Stable energy metabolism, balanced inflammatory responses, appropriate appetite and glucose regulation.

DYSREGULATION

Metabolic dysregulation, fatigue associated with inflammatory activity, altered appetite regulation, variable response to dietary or metabolic interventions.

Associated conditions
Obesity, type 2 diabetes, NAFLD³

Physiological Function Summary

PATHWAY

HEALTHY FUNCTION

DYSREGULATION

Immune regulation

Immune tolerance, controlled inflammatory responses

Inflammatory symptoms, altered immune sensitivity

Barrier integrity

Stable digestion, selective permeability

Bloating, bowel disruption, food sensitivity

Metabolic signalling

Stable energy metabolism, glucose regulation

Metabolic dysregulation, variable treatment response

Systemic signalling

Coordinated neuroimmune and enteroendocrine signalling

Disrupted gut–brain communication, variable systemic signalling

The microbiome influences chronic disease through core physiological functions

Chronic diseases rarely arise from disruption of a single biological pathway. Instead, they typically involve dysregulation across interconnected physiological functions, including metabolism, immune regulation, gut barrier integrity, and systemic signalling^.1

In clinical practice, dysbiosis should not be interpreted simply as the presence of a pathogen or depletion of a single “beneficial” organism.  More commonly, dysbiosis reflects broader shifts in microbial ecology and metabolic output that interact with existing clinical vulnerabilities.

What this looks like in practice

inflammatory regultion

Microbial metabolites, including short-chain fatty acids (SCFAs) and some indole derivatives, play an important role in immune regulation. These compounds influence immune cell differentiation, cytokine production and inflammatory signalling.⁸ Reduced SCFA-producing capacity has been associated with conditions characterised by immune dysregulation, including inflammatory bowel disease, autoimmune disorders and the low-grade systemic inflammation observed in metabolic syndrome.^5,8

Clinical presentations

The following clinical presentations have been associated with microbiome-related immune dysregulation. Causal relationships are not established for all; these associations should be interpreted in the context of each patient’s clinical picture.^1,8

Barrier integrity

The intestinal epithelium forms a critical interface between luminal microbial communities and the host immune system. Microbial metabolites such as butyrate support epithelial energy metabolism, tight junction integrity and mucosal immune signalling.⁹ When epithelial barrier regulation is disrupted, microbial products such as hexa-acylated lipopolysaccharides (hexa-LPS) may cross the intestinal barrier more readily, promoting immune activation and inflammatory signalling.^1,9

Clinical presentations

The following clinical presentations have been associated with microbial disruption in the literature.
Causal relationships are not established for all; these associations should be interpreted in the context of each patient’s clinical picture

Metabolism

Gut microbes participate in nutrient metabolism and energy regulation through the production of bioactive metabolites that interact with metabolic pathways. Alterations in microbial metabolic activity have been associated with differences in glycaemic control, energy homeostasis and systemic inflammatory tone.¹²

Clinical presentations ^1,13

Systemic signalling

Microbial products can influence signalling beyond the gut through several recognised routes, including enteroendocrine signalling, gut-innervating afferent nerves such as the vagus nerve, and immune pathways^.1,13 Short-chain fatty acids, tryptophan-derived metabolites, and hexa-acylated lipopolysaccharides can act on enteroendocrine and immune cells, modulate cytokine signalling,  and influence neuronal communication between the gut and brain.¹³

These interactions are bidirectional. Factors such as diet, immune status, medications and environmental exposures continuously shape microbial ecology, while microbial metabolites in turn influence immune regulation, gut barrier integrity, metabolism and systemic signalling. Patients with similar diagnoses can respond differently to the same interventions — differences in microbial metabolism are increasingly recognised as a contributing factor.^1,8,9

Did you know?

These interactions are bidirectional. Diet, immune status, medication exposure and environmental factors continuously shape microbial ecology, while microbial metabolites in turn influence immune function, epithelial integrity and metabolic regulation. Patients with similar diagnoses can respond differently to the same interventions — differences in microbial metabolism are increasingly recognised as a contributing factor.^8,9,10

Simplified microbiome models are not sufficient for clinical practice

Wellness messaging often reduces the microbiome to simplified concepts such as “good versus bad bacteria” or the idea that gut health can be restored by simply “rebalancing” microbial populations.  These narratives are appealing because they are easy to communicate, but they do not reflect how microbial ecosystems function within human physiology.

Clinical science approaches the microbiome differently. Rather than focusing on individual organisms classified as beneficial or harmful, it considers microbial communities as dynamic ecosystems whose effects depend on ecological structure, functional capacity and host context.³

Wellness framing

“Good vs bad bacteria.” Rebalance with a single product.
One-size-fits-all interventions. No consideration of individual ecology or patient context.

Clinical science

Dynamic ecosystems. Functional capacity and ecological structure. Strain-level differences. Context-dependent metabolic effects. Bidirectional microbiome signalling.

This approach also reflects the clinical and regulatory standards that govern medical practice. In medical contexts, health claims must be supported by robust scientific evidence, which is why clinical microbiome research avoids overstating conclusions and remains grounded in established biological mechanisms.

As a result, interventions based purely on simplified microbial classifications may produce inconsistent outcomes. Two individuals taking the same probiotic, dietary intervention or supplement may experience different effects depending on their existing microbial ecology, metabolic pathways and host physiology.¹⁶

When microbiome interventions are selected without consideration of the clinical presentation, they may not target the biological mechanisms contributing to a patient’s symptoms. In some cases, this may result in minimal benefit, transient improvement or variability in response between individuals.

A clinically responsible framework therefore recognises several principles supported by microbiome research:

Substantial variation: there is substantial variation in microbial composition between individuals, even among healthy population

Functional differences at species and strain level that influence metabolic activity

Context-dependent metabolic effects rather than outcomes determined by the presence of a single organism

Bidirectional signalling between host physiology and microbial activity ^3,4,16,17

Key Takeaway

For clinicians, microbiome insights provide an additional lens for understanding systemic regulation, particularly in chronic and complex symptom patterns.

1. Fan Y, Pedersen O. Gut microbiota in human metabolic health and disease. Nat Rev Microbiol. 2021;19(1):55–71. https://doi.org/10.1038/s41579-020-0433-9
2. Lynch SV, Pedersen O. The human intestinal microbiome in health and disease. N Engl J Med. 2016;375(24):2369–2379. https://doi.org/10.1056/NEJMra1600266
3. Wilde J, Slack E, Foster KR. Host control of the microbiome: Mechanisms, evolution, and disease. Science. 2024;385(6706):eadi3338. https://doi.org/10.1126/science.adi3338
4. Human Microbiome Project Consortium. Structure, function and diversity of the healthy human microbiome. Nature. 2012;486(7402):207–14.
5. Mann ER, Lam YK, Uhlig HH. Short-chain fatty acids: linking diet, the microbiome and immunity. Nat Rev Immunol. 2024;24(8):577–595. https://doi.org/10.1038/s41577-024-01014-8
6. de Vos WM, Tilg H, Van Hul M, Cani PD. Gut microbiome and health: mechanistic insights. Gut. 2022;71(5):1020–1032. https://doi.org/10.1136/gutjnl-2021-326789
7. Zhou X, Shen X, Johnson JS, et al. Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease. Cell Host Microbe. 2024;32(4):506–526.e9.
8. Hays KE, Pfaffinger JM, Ryznar R. The interplay between gut microbiota, short-chain fatty acids, and implications for host health and disease. Gut Microbes. 2024;16(1):2393270. https://doi.org/10.1080/19490976.2024.2393270
9. Ornelas A, Dowdell AS, Lee JS, Colgan SP. Microbial Metabolite Regulation of Epithelial Cell-Cell Interactions and Barrier Function. Cells. 2022;11(6):944.
10. Honda K, Littman DR. The microbiota in adaptive immune homeostasis and disease. Nature. 2016;535(7610):75–84. https://doi.org/10.1038/nature18848
11. Koh A, De Vadder F, Kovatcheva-Datchary P, Bäckhed F. From dietary fiber to host physiology: short-chain fatty acids as key bacterial metabolites. Cell. 2016;165(6):1332–1345. https://doi.org/10.1016/j.cell.2016.05.041
12. Muramatsu MK, Winter SE. Nutrient acquisition strategies by gut microbes. Cell Host Microbe. 2024;32(6):863–874. https://doi.org/10.1016/j.chom.2024.05.011
13. Cryan JF, O’Riordan KJ, Cowan CSM, et al. The microbiota-gut-brain axis. Physiol Rev. 2019;99(4):1877–2013. https://doi.org/10.1152/physrev.00018.2018
14. Lloyd-Price J, Arze C, Ananthakrishnan AN et al. Multi-omics of the gut microbial ecosystem in inflammatory bowel diseases. Nature. 2019;569(7758):655–662. https://doi.org/10.1038/s41586-019-1237-9
15. Staudacher HM, Mikocka-Walus A, Ford AC. Common mental disorders in irritable bowel syndrome: pathophysiology, management, and considerations for future randomised controlled trials. Lancet Gastroenterol Hepatol. 2021;6(5):401–410. https://doi.org/10.1016/S2468-1253(20)30363-0
16. Leshem A, Segal E, Elinav E. The Gut Microbiome and Individual-Specific Responses to Diet. mSystems. 2020;5(5):e00665-20.
17. Zmora N, Suez J, Elinav E. You are what you eat: diet, health and the gut microbiota. Nat Rev Gastroenterol Hepatol. 2019;16(1):35–56. https://doi.org/10.1038/s41575-018-0061-2

Microbial diversity protects against pathogens through colonisation resistance

One of the microbiome’s key roles is protecting against harmful microorganisms, a process called colonisation resistance. In a diverse, well-balanced community, many species compete for space and nutrients, leaving few open niches for potential pathogens to occupy. Other mechanisms of colonisation resistance include the production of acidic metabolites that lower luminal pH, antimicrobial compounds, and metabolites that support barrier function and host immunity.^4,5,6,7

Did you know?

When diversity is reduced — after antibiotics, severe illness or restrictive diets — this protective network can weaken. With fewer competitors and less functional redundancy (fewer microbes able to perform the same protective functions), opportunistic organisms may gain a foothold and, in some cases, establish infection or persistent colonisation.^4,7

Clinical example

Impaired colonisation resistance has been linked to greater susceptibility to post-infectious IBS following gastroenteritis, with some individuals experiencing long-term symptoms after an acute infection. ^8,9

Diet determines microbial outputs

The same microbes can produce different metabolites

What microbes do is strongly influenced by what they are fed. Many dietary fibres cannot be digested by human enzymes but can be fermented by gut microbes, producing health-promoting short-chain fatty acids (SCFAs). 10,11 Microbes also ferment undigested protein and amino acids in the distal colon, producing metabolites that may be harmful or beneficial. ¹⁰

Critically, the gut microbiota is metabolically flexible. Microbes that produce beneficial metabolites from dietary fibre can shift towards less favourable outputs when the diet is low in fermentable carbohydrates and high in protein or fat. ^10,13
The type and diversity of fibre matter as much as total fibre.

Microbial metabolites shape immune function across the lifespan

From birth, the immune system learns to distinguish between threats and harmless exposures. Early contact with diverse microbes supports the development of regulatory pathways that reduce the risk of over-reactive responses. Disruptions in early-life microbial exposure have been associated with increased risk of allergies, asthma, inflammatory bowel disease and autoimmune conditions.²¹

In adulthood, the microbiome continues to shape immune function: Microbiota-derived SCFAs can promote regulatory immune responses. ^14,24 Similarly, tryptophan-derived metabolites can modulate innate immune responses. ²⁵ Lipopolysaccharides (bacterial cell wall components) can either trigger or dampen inflammatory signalling. ²⁶ When the microbiome is balanced, these signals usually support a steady, controlled immune state. ²⁷

Clinical example

In oncology, gut microbiome composition has been linked to better or worse responses to immunotherapy, suggesting microbial immune modulation can influence treatment outcomes.²⁸

Health outcomes depend on community cooperation, not individual organisms

Many clinically relevant metabolites are not produced by a single microbe acting alone. Instead, they arise through cross-feeding, where one species’ metabolic by-products become another species’ fuel. People with very different species profiles can still display similar functional capacities: different microbial “teams” can lead to similar metabolic outcomes.^3,29

Clinical example

After antibiotic courses, some individuals develop prolonged bloating, pain and altered bowel habits. Studies have reported disrupted cross-feeding networks and lower SCFA production in these settings, consistent with loss of key metabolic partners and reduced ecosystem resilience.³⁰

Functional potential only becomes functional reality when the right conditions align

Modern sequencing technologies can estimate the microbiome’s functional potential by identifying genes and pathways — a valuable starting point. However, this potential must be realised through the right conditions, and especially fuel source availability.³

Because healthy people can have very different species profiles, it is difficult to define a single “ideal” microbiome based only on who is present.

It is more practical to think in terms of functional balance: a state where activities that support health are robust, while pathways that generate potentially harmful metabolites are kept in check.³¹

FUNCTIONAL POTENTIAL

Genes and pathways are present

↓

RIGHT CONDITIONS

Available fibre, substrates, microbial cooperation, gut environment

↓

FUNCTIONAL REALITY

Metabolites are actively produced

Key Takeaway

The microbiome is a dynamic ecosystem whose functions — not just its composition — shape human health. Diverse communities support colonisation resistance, diet along with other factors determine metabolic outputs, and health outcomes depend on community cooperation and functional balance rather than individual species.

Functional potential only becomes functional reality when the right fuels and conditions align. A functional, ecosystem-based lens supports more personalised, targeted strategies to maintain or restore health.

Coyte KZ, Schluter J, Foster KR. The ecology of the microbiome: networks, competition, and stability. Science. 2015;350:663–666.
Schroeder BO, Bäckhed F. Signals from the gut microbiota to distant organs in physiology and disease. Nat Med. 2016;22:1079–1089.
Human Microbiome Project Consortium. Structure, function and diversity of the healthy human microbiome. Nature. 2012;486:207–214.
Sorbara MT, Pamer EG. Interbacterial mechanisms of colonization resistance. Mucosal Immunol. 2019;12:1–9.
Caballero-Flores G, Pickard JM, Núñez G. Microbiota-mediated colonization resistance. Nat Rev Microbiol. 2023;21:347–360.
Kamada N, Chen GY, Inohara N, Núñez G. Control of pathogens and pathobionts by the gut microbiota. Nat Immunol. 2013;14:685–690.
Buffie CG, Pamer EG. Microbiota-mediated colonization resistance against intestinal pathogens. Nat Rev Immunol. 2013;13:790–801.
Jalanka J, Gunn D, Singh G, Krishnasamy S, Lingaya M, Crispie F, et al. Postinfective bowel dysfunction following Campylobacter enteritis. Gut. 2023;72:451–459.
Marshall JK, Thabane M, Garg AX, Clark WF, Moayyedi P, Collins SM. Eight year prognosis of postinfectious IBS. Gut. 2010;59:605–611.
Rowland I, Gibson G, Heinken A, Scott K, Swann J, Thiele I, et al. Gut microbiota functions: metabolism of nutrients and other food components. Eur J Nutr. 2018;57:1–24.
Koh A, De Vadder F, Kovatcheva-Datchary P, Bäckhed F. From dietary fiber to host physiology: SCFAs as key bacterial metabolites. Cell. 2016;165:1332–1345.
Peng L, Li ZR, Green RS, Holzman IR, Lin J. Butyrate enhances the intestinal barrier. J Nutr. 2009;139:1619–1625.
Gilbert MS, Ijssennagger N, Kies AK, van Mil SWC. Protein fermentation in the gut. Am J Physiol Gastrointest Liver Physiol. 2018;315:G159–G170.
Corrêa-Oliveira R, Fachi JL, Vieira A, Sato FT, Vinolo MAR. Regulation of immune cell function by short-chain fatty acids. Clin Transl Immunol. 2016;5:e73.
Alexeev EE, Lanis JM, Kao DJ, Campbell EL, Kelly CJ, Battista KD, et al. Microbiota-derived indole metabolites promote intestinal homeostasis through regulation of interleukin-10 receptor. Am J Pathol. 2018;188:1183–1194.
Canfora EE, Jocken JW, Blaak EE. Short-chain fatty acids in control of body weight and insulin sensitivity. Nat Rev Endocrinol. 2015;11:577–591.
Sinha AK, Laursen MF, Brinck JE, Rybtke ML, Hjørne AP, Procházková N, et al. Dietary fibre directs microbial tryptophan metabolism via metabolic interactions in the gut microbiota. Nat Microbiol. 2024;9:1964–1978.
Teichmann J, Cockburn DW. Butyrate production dependent on resistant starch source. Front Microbiol. 2021;12:640253.
Venkataraman A, Sieber JR, Schmidt AW, Waldron C, Theis KR, Schmidt TM. Variable responses to dietary supplementation with resistant starch. Microbiome. 2016;4:33. 20. Ďásková N, Modos I, Krbcová M, Kuzma M, Pelantová H, Hradecký J, et al. Multi-omics signatures predict metabolic response to dietary inulin. Nutr Diabetes. 2023;13:7.
Gensollen T, Iyer SS, Kasper DL, Blumberg RS. How colonization by microbiota in early life shapes the immune system. Science. 2016;352:539–544.
Wernroth M-L, Fall K, Svennblad B, Ludvigsson JF, Sjölander A, Almqvist C, et al. Early childhood antibiotic treatment is associated with risk of type 1 diabetes. Diabetes Care. 2020;43:991–999.
Kronman MP, Zaoutis TE, Haynes K, Feng R, Coffin SE. Antibiotic exposure and IBD development among children. Pediatrics. 2012;130:e794–e803.
Arpaia N, Campbell C, Fan X, Dikiy S, van der Veeken J, deRoos P, et al. Metabolites produced by commensal bacteria promote peripheral regulatory T-cell generation. Nature. 2013;504:451–455.
Zelante T, Iannitti RG, Cunha C, De Luca A, Giovannini G, Pieraccini G, et al. Tryptophan catabolites from microbiota engage aryl hydrocarbon receptor. Immunity. 2013;39:372–385.
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Culp EJ, Goodman AL. Cross-feeding in the gut microbiome. Cell Host Microbe. 2023;31:485–499.
Palleja A, Mikkelsen KH, Forslund SK, Kashani A, Allin KH, Nielsen T, et al. Recovery of gut microbiota following antibiotic exposure. Nat Microbiol. 2018;3:1255–1265.
Tiffany CR, Bäumler AJ. Dysbiosis: from fiction to function. Am J Physiol Gastrointest Liver Physiol. 2019;317:G602–G608.

For healthcare practitioners, the clinical question is straightforward: can we measure a patient’s gut microbiome accurately enough, and interpret the results rigorously enough, to inform care?

Accurate gut measurement depends on getting the foundations right

001

MEASUREMENT TECHNOLOGY

The sequencing method used to capture the microbial community and its resolution, coverage, and accuracy

002

REFERENCE DATA QUALITY

The reference cohort against which results are compared and whether it eliminates technical and biological bias

003

SCIENTIFIC FRAMEWORK

The evidence curation applied to translate microbial signals into meaningful, clinically relevant context

Many gut health tests available today rely on older methods — culture-based assays, quantitative PCR (qPCR), or 16S ribosomal RNA (rRNA) gene sequencing — that provide only a partial view of the microbiome. These approaches can be good in specific circumstances (e.g. identification of pathogens), but have well-documented limitations in taxonomic resolution, coverage of the entire microbiome, and the ability to assess microbial function.^6,7  The emergence of shotgun metagenomics — sequencing all DNA in a sample rather than a single gene — has fundamentally changed what is possible, enabling species- and even strain-level identification alongside functional pathway analysis.⁸

MICROBA MICROBIOME EXPLORER

A comprehensive gut health test
built on all three

Microba Microbiome Explorer combines accredited gastrointestinal diagnostics with high-resolution shotgun metagenomic microbiome profiling. This deep dive covers the complete scientific and technological foundation — from how a sample is preserved, through to the clinical insights a practitioner reads in the report.

001 SAMPLE PRESERVATION

002 ACCREDITED LABORATORY

003 SHOTGUN METAGENOMICS

004 PEER-REVIEWED BIOINFORMATICS

005 THREE-LAYER TEST COMPOSITION

006 THREE-TIER EVIDENCE CURATION

007 HEALTHY REFERENCE GROUP

008 EVIDENCE-GRADED CLINICAL INSIGHTS

Underpinning the test is a proprietary technology stack: a validated sample preservation system, a highly automated sequencing laboratory that has processed more than 100,000 metagenomes, and the Microba Community Profiler (MCP) — a peer-reviewed bioinformatic classifier that achieves highly accurate species identification in faecal samples.

100,000+

Metagenomes processed Operational track record

28,000+

Species assessed Species-level profiling

99%

Precision rate Virtually zero false positives

19,000+%

Consented profiles Internal validation dataset

Microba has developed a comprehensive gut health test — Microba Microbiome Explorer — that combines accredited gastrointestinal diagnostics with high-resolution shotgun metagenomic microbiome profiling.
The diagnostic components (pathogen detection and gastrointestinal markers) are CE-certified and run within an ISO 15189 NATA-accredited medical laboratory. The microbiome component is for research use only and provides species-level profiling and functional insights that go beyond what legacy testing methods can offer.

Did you know?

Microbial markers are scientifically curated using a rigorous three-tier evidence framework, and results are compared against a carefully defined healthy reference group of more than 450 individuals.

SAMPLE COLLECTION

Validated sample preservation
protects the accuracy of every result

The accuracy of any microbiome test begins with sample integrity. Faecal samples are biologically active, and microbial composition can shift rapidly after collection if not properly preserved. Microba uses the Copan FLOQSwab in an active-drying tube (FLOQSwab-ADT) that has been rigorously benchmarked against commonly used preservation methods, including OMNIgene-GUT, RNAlater, BBL dry cotton swabs, and LifeGuard.⁹

In a peer-reviewed evaluation, Microba’s swab demonstrated the best performance for both technical (between-replicate) reproducibility and compositional stability relative to flash-frozen controls. Additionally, a second experiment in the same study demonstrated that the FLOQSwab-ADT maintained its performance across storage at -20°C, room temperature, and 50°C for four weeks, making it suitable for postal collection in a wide range of climatic conditions.⁹

Best reproducibility

Highest technical (between-replicate) reproducibility and compositional stability relative to flash-frozen controls in a peer-reviewed evaluation

Climate resilient

Stable across -20°C, room temperature, and 50°C for four weeks — suitable for postal collection Australia-wide

This means practitioners can be confident that the microbial profile generated from a swab collected at home closely reflects the true composition of the patient’s sample at the time of collection.

001

Patient collects
at home

002

FLOQSwab-ADT
preserves sample

003

Postal delivery in
any climate

004

Microba lab receives
intact sample

LABORATORY PROCESSING

An ISO 15189 accredited laboratory has
processed over 100,000 metagenomes

Microba operates an ISO 15189 NATA-accredited medical testing laboratory — the internationally recognised standard for medical laboratories. The laboratory uses the latest DNA sequencing technology and maintains a high level of automation, from sample receipt through to data generation. An automated quality control pipeline monitors every sample, flagging any that fall outside predefined quality thresholds. To date, the laboratory has processed more than 100,000 metagenomes, providing a substantial operational track record.

How does it work?

The software systems used to analyse and interpret metagenomic data are developed under an ISO 13485 quality management system for software as a medical device. This dual accreditation — ISO 15189 for laboratory processes and ISO 13485 for software — reflects a commitment to clinical-grade quality at every stage.

001

SAMPLE RECEIPT

002

DNA EXTRACTION

003

SEQUENCING

004

DATA GENERATION

DUAL ACCREDITATION

ISO 15189

Internationally recognised standard for medical laboratory processes —
covering sample receipt, sequencing, and data generation

ISO 13485

Quality management system for software as a medical device —
covering the bioinformatic analysis and interpretation pipeline

Sequencing technology

Shotgun metagenomics identifies species that other methods miss entirely

Shotgun metagenomics sequences all DNA extracted from a faecal sample, providing a comprehensive and relatively unbiased view of the entire microbial community.⁸
This allows identification of organisms at the species level — a critical capability, because different species within the same genus can have very different roles in health.
For example, Streptococcus thermophilus is a beneficial organism widely used in dairy fermentation, while Streptococcus anginosus is an opportunistic pathogen associated with abscess formation. A test that identifies only the genus Streptococcus cannot distinguish between these two very different clinical scenarios.

Taxonomic Resolution

Coverage

Functional Profiling

Novel Species Detection

PCR Bias

16S RRNA

Genus level

Bacteria and Archaea only

Not possible

Yes

QPCR / CULTURE

Predefined targets only

Limited panel

Yes

SHOTGUN METAGENOMICS

Species and strain level

Bacteria, Archaea, eukaryotes

Gene and pathway level

Yes

Minimal

632 species vs 57

In a direct comparison, shotgun metagenomics identified 632 species in a sample where 16S sequencing detected only 57 — an order-of-magnitude difference in resolution that directly affects clinical utility.

Sequencing technology

Shotgun metagenomics
enables functional profiling

Equally important, shotgun metagenomics enables functional profiling — identifying the metabolic genes and pathways present across the entire microbial community. This makes it possible to assess the community’s capacity to produce health-relevant metabolites such as butyrate, or to carry out processes such as mucin degradation, providing a functional layer of information that 16S sequencing cannot accurately deliver.

18.96%

Butyrate-producing capacity detected across the microbial community — even when measured metabolite output appeared low.

Some tests reporting low short-chain fatty acid metabolites (measured via GC/MS) missed the broader picture. Microba’s community-level assessment showed 18.96% butyrate-producing capacity in the microbial community — indicating the functional machinery was present even when measured metabolite output appeared low. This shifts the clinical question from whether the microbiome is capable of producing butyrate to whether the right dietary substrates are available to support that production. 16S sequencing cannot deliver this functional layer of information — it identifies organisms but cannot assess which metabolic genes and pathways are present across the community.⁸

Bioinformatics

The Microba Community Profiler achieves  99% precision — peer-reviewed and benchmarked

Generating sequence data is only the first step. The accuracy of a microbiome profile depends critically  on the bioinformatic tools used to classify the millions of short DNA sequences (reads) produced by a sequencing run. The Microba Community Profiler (MCP) is a proprietary whole-genome alignment tool  that classifies metagenomic reads to produce species-level community profiles. Its performance has been rigorously benchmarked in a peer-reviewed study published in Frontiers in Microbiology, where it was evaluated against nine widely used academic classifiers across 140 simulated microbial communities of varying complexity.

PRECISION (% — HIGHER IS BETTER)

Highest accuracy

MCP achieved the highest combined precision and recall across all tested conditions, outperforming all other evaluated classifiers by five to 20 percentage points.

Fewest false positives

MCP achieved 99% precision, meaning that virtually every species it reports is genuinely present in the sample.  It produced four to 16 times fewer false positive species predictions than other classifiers — a critical advantage, because false positives can mislead clinical interpretation.

Lowest detection limit

MCP demonstrated the ability to reliably detect species at abundances 20 to 60 times lower than competing tools, with a detection limit as low as 0.007% at a false discovery rate of 0.1%.

Accurate abundance estimates

The relative abundance estimates produced by MCP closely matched the known ground-truth abundances in simulated communities, performing equivalently or better than other leading classifiers.

A unique advantage of MCP is that it automatically filters species predictions to report only those with high confidence, without requiring the user to manually set abundance thresholds. Most other classifiers report thousands of low-abundance false positives unless the user manually inspects and filters the output.⁵

TEST COMPOSITION

Three integrated layers connect microbial presence to measurable clinical markers

Microba Microbiome Explorer is a comprehensive gut health test that integrates three layers of information:

PATHOGEN DETECTION

A panel of 13 common bacterial pathogens and five parasites detected via CE-certified multiplex PCR assays.

HUMAN STOOL MARKERS

Six GI health markers including calprotectin, lactoferrin, faecal occult blood, secretory IgA, pancreatic elastase, and zonulin — assessed using CE-certified immunohistochemistry assays. Faecal pH is also measured as an investigative marker for research use only.

MICROBIOME PROFILING

Species-level profiling of 28,000+ species including microbial diversity, richness, and 16 health-associated functional markers — such as butyrate production, trimethylamine, hexa-acylated lipopolysaccharides, mucin degradation, and oxalate consumption. For research use only.

By combining diagnostic gastrointestinal markers with microbiome profiling, the test moves beyond simple species detection to provide a functional picture of gut health — linking what is present in the microbiome with measurable clinical markers of gut function and inflammation.

SCIENTIFIC CURATION

Only markers passing all three evidence tiers are included in the report

Not every microbial signal is clinically meaningful. To ensure that the microbiome markers reported in the test are supported by robust evidence, Microba applies a rigorous three-tier scientific curation framework. Only markers that satisfy all three tiers (with limited, clearly disclosed exceptions) are included in the report.*

*Exceptions in Microbiome Explorer: acetate and intestinal inflammation (mechanism only), beta-glucuronidase and impaired detoxification (mechanism only) and Emerging Markers.”

Plausible mechanism of action

SCFA production, immune regulation, barrier maintenance and colonisation resistance are robust. Pathways generating potentially harmful metabolites are kept in check.

Example: The link between mucin-degrading species and intestinal inflammation is supported by mechanistic studies showing that depletion of the mucus barrier increases microbial proximity to the epithelium, driving immune activation.^10,13

Reproducible human associations

At least two peer-reviewed human studies must demonstrate a direct or indirect association between the microbial marker and the health outcome.

Example: Direct evidence includes correlation of the marker with a clinical measure, such as oral species abundance and faecal calprotectin. Indirect evidence includes correlation with relevant diseases, or plasma levels of the microbial marker with a clinical measure.^14,15

Significant associations in Microba’s dataset

The microbial marker must demonstrate a statistically significant association with a minimum small effect size in Microba’s database of more than 19,000 consented metagenomic profiles with linked health and lifestyle data. Analyses are controlled for age, sex, BMI, and Bristol stool index.

Example: This internal validation step ensures that markers are not only supported by published literature but are also reproducible in a large, independent cohort processed through Microba’s own laboratory and analysis pipeline.

Reference data

A carefully defined healthy reference group of 450+ individuals eliminates technical bias

To determine whether a patient’s microbiome markers are within a healthy range, results must be compared against an appropriate reference group. Many commercially available tests either provide no details about their reference cohort, use publicly available microbiome data (which introduces significant variability due to differences in sample collection, processing, and analysis methods), or compare samples against their entire database regardless of health status.

Microba’s healthy reference group has been carefully selected and includes more than 450 individuals who meet strict inclusion criteria. Critically, all reference samples were collected and processed using exactly the same workflow as patient test samples, eliminating a common source of technical bias.

INCLUSION CRITERIA
No major medical conditions

No or minimal GI symptoms· Mild or lower stress, anxiety, and depression

BMI below 30 Daily fruit and vegetable intake

Low to moderate alcohol consumption

CLINICAL INSIGHTS

Evidence-graded actions give practitioners
a clear basis for clinical conversations

Generating accurate microbiome data is necessary but not sufficient. For gut health testing to be clinically useful, the data must be translated into interpretable insights that healthcare practitioners can act upon.

In Microba’s Microbiome Explorer, microbial markers and gastrointestinal markers are organised into health categories that correspond to recognisable clinical concepts. Each health category provides a clear interpretation of whether the patient’s results fall within or outside the healthy reference range, and, where applicable, links to the relevant diagnostic GI markers for clinical correlation.

INTESTINAL INFLAMMATION

SYSTEMIC INFLAMMATION

GUT MOTILITY

GUT BARRIER FUNCTION

METABOLIC HEALTH

PATHOGEN PRESENCE

When a marker is identified as out of range, the report provides evidence-graded possible actions. Microba’s science team has undertaken a rigorous review of the available scientific evidence for different dietary, supplement, or lifestyle interventions to modulate microbial functions and graded these using the NHMRC evidence grading framework. Each listed action is accompanied by the evidence grade and hyperlinks to the references that informed the grade.

WORKED EXAMPLE

Mucin degradation and intestinal
inflammation

The proportion of mucin-degrading species in the microbiome is one of the markers assessed in the test. The mechanistic basis for this marker is well established: when dietary fibre is insufficient, mucin-degrading microbes consume the protective mucus layer lining the gut, increasing microbial contact with the intestinal epithelium and triggering immune activation.

A large cross-sectional study of more than 1,000 individuals found a significant positive association between mucin-degrading pathway abundance and faecal calprotectin (a clinical marker of intestinal inflammation). Elevated mucin degrading pathways have also been observed in colorectal cancer cohorts.

In Microba’s own dataset, the relative abundance of mucin-degrading species is significantly increased in several health conditions related to intestinal inflammation compared to healthy controls, after controlling for confounders.

Microscopy image related to intestinal inflammation

This layered approach — mechanistic plausibility, published human evidence, and internal validation — gives practitioners a clear rationale for each marker and a basis for evidence-informed clinical conversations with patients. Microba Microbiome Explorer is exclusively offered through healthcare professionals. This distribution model ensures that results are interpreted accurately, responsibly, and in the best interests of patient care.

What makes Microba’s
approach different

The gut health testing market includes a range of products built on different technologies, evidence standards, and quality systems. Several features distinguish Microba’s approach from legacy and competing tests.

High-resolution metagenomics,
not 16S or qPCR

While many commercial gut tests rely on 16S rRNA gene sequencing (which typically resolves only to genus level) or targeted qPCR panels (which assess only a predefined list of organisms), Microba uses shotgun metagenomics to deliver species-level resolution across the entire microbial community. In a direct comparison, shotgun metagenomics identified 632 species in a sample where 16S sequencing detected only 57.

Whole-microbiome functional assessment

Some competing tests claim to provide functional information but assess only a handful of known species associated with a particular function. Microba’s functional markers assess the capacity of the entire microbial community to perform a given metabolic function — for example, butyrate production across all species that carry the relevant genes.

Peer-reviewed,
benchmarked bioinformatics

The Microba Community Profiler has been formally benchmarked against nine other classifiers in a peer-reviewed study and demonstrated the highest accuracy and lowest false-positive rate. Many competing tests do not disclose their bioinformatic methods or provide evidence of benchmarking.

Rigorous three-tier
evidence curation

Microba’s three-tier marker curation framework — requiring mechanistic plausibility, reproducible human associations, and internal dataset validation — stands in contrast to many tests that include numerous “microbiome scores” or “gut-axis” risk associations with limited or no published scientific support.

Like-for-like healthy
reference group

By defining a reference group with strict health criteria and processing all reference samples through the same workflow as patient samples, Microba eliminates a significant source of technical and biological confounding that affects tests relying on public databases or heterogeneous internal cohorts.

Dual accreditation

The combination of ISO 15189 medical laboratory accreditation and ISO 13485 software-as-a-medical-device certification reflects a level of quality assurance that is uncommon among commercial microbiome test providers.

Transparency about limitations is essential for responsible clinical use

The microbiome component of Microba Microbiome Explorer is for research use only and is  not a diagnostic tool. Microbiome results should be interpreted by qualified healthcare practitioners in  the context of a patient’s clinical history, symptoms, and other diagnostic findings.

The test does not diagnose, treat, or prevent any disease. Like all sequencing-based microbiome  tests, Microba’s metagenomic profiling produces compositional data — it measures the relative proportions of different species rather than their absolute quantities. This is an inherent characteristic  of current sequencing technology and means that changes in the abundance of one organism can influence the apparent abundance of others.

Microba's reference database, while comprehensive, does not capture the full diversity of the human gut microbiome.

On average, Microba will be able to assign a species ID to 82.4% of sequencing reads. Microba continues to expand the database with newly identified species and strains, and ongoing updates to the reference database aim to increase the proportion of sequencing reads assigned a species ID and lower detection limits further.

The marker curation framework is also a living process: as new evidence emerges, markers may be added, refined, or retired. Future directions include further validation studies, expansion of the healthy reference group to include additional populations, and continued development of evidence-graded suggested actions informed by the latest intervention research.

A considered integration of science,
evidence, and quality

Microba’s Microbiome Explorer represents a considered integration of advanced metagenomic science, rigorous evidence curation, and accredited laboratory quality. By combining CE-certified gastrointestinal diagnostics with high-resolution microbiome profiling, the test provides healthcare practitioners with a comprehensive view of gut health that goes well beyond what legacy testing methods can offer.

Every layer of the technology stack — from validated sample preservation and automated laboratory processing, through to the peer-reviewed MCP — has been designed to maximise accuracy and minimise the risk of misleading results. The three-tier marker curation framework ensures that only microbial markers with robust supporting evidence are included, and results are compared against a carefully curated healthy reference group.

Microba commitment

While the microbiome component remains for research use only, the depth and quality of information it provides can support practitioners in building a more complete understanding of their patients’ gastrointestinal health.

As the science of the microbiome continues to advance, Microba is committed to translating that science into testing that practitioners can trust.

Sample collection

Validated FLOQSwab-ADT
Climate-resilient postal collection

Lab + data generation

ISO 15189 accredited lab
100,000+ metagenomes
Automated QC pipeline

Core analysis (the “engine”)

Shotgun metagenomics
Microba Community Profiler (99% precision)

Interpretation layer

Three-tier evidence curation
450+ healthy reference group
NHMRC-graded actions

Final output

Clinically useful insights for practitioners

. Lynch, S. V. & Pedersen, O. The human intestinal microbiome in health and disease. N. Engl. J. Med. 375, 2369–2379 (2016). https://doi.org/10.1056/NEJMra1600266
2. Gilbert, J. A., Blaser, M. J., Caporaso, J. G., Jansson, J. K., Lynch, S. V. & Knight, R. Current understanding of the human microbiome. Nat. Med. 24, 392–400 (2018). https://doi.org/10.1038/nm.4517
3. Fan, Y. & Pedersen, O. Gut microbiota in human metabolic health and disease. Nat. Rev. Microbiol. 19, 55–71 (2021). https://doi.org/10.1038/s41579-020-0433-9
4. Zmora, N., Suez, J. & Elinav, E. You are what you eat: diet, health and the gut microbiota. Nat. Rev. Gastroenterol. Hepatol. 16, 35–56 (2019). https://doi.org/10.1038/s41575-018-0061-2
5. Parks, D. H., Rigato, F., Vera-Wolf, P., Krause, L., Hugenholtz, P., Tyson, G. W. & Wood, D. L. A. Evaluation of the Microba Community Profiler for taxonomic profiling of metagenomic datasets from the human gut microbiome. Front. Microbiol. 12, 643682 (2021). https://doi.org/10.3389/fmicb.2021.643682
6. Jovel, J., Patterson, J., Wang, W., Hotte, N., O’Keefe, S., Mitchel, T. et al. Characterization of the gut microbiome using 16S or shotgun metagenomics. Front. Microbiol. 1591-019-0406-6
7, 459 (2016). https://doi.org/10.3389/fmicb.2016.00459
7. Sczyrba, A., Hofmann, P., Belmann, P., Koslicki, D., Janssen, S., Dröge, J. et al. Critical assessment of metagenome interpretation — a benchmark of metagenomics software. Nat. Methods 14, 1063–1071 (2017). https://doi.org/10.1038/nmeth.4458
8. Hugenholtz, P. & Tyson, G. W. Metagenomics. Nature 455, 481–483 (2008). https://doi.org/10.1038/455481a

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Everything you need to choose and use the right test

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The gut microbiome is a measurable biological system

The healthy function of the microbiome depends on a balanced ecosystem

Microbial interactions are shaped by balance, not fixed labels

Microbes convert fuel into compounds that influence health

Key helpful functions of the gut microbiome

The microbiome functions as part of human biology — not separate from it.

It’s not enough to know which microbes are present, you need to know what the ecosystem is doing

Microbiome insight adds a systems-level lens to clinical care.

Key Takeaway

Explore the complete article

The gut microbiome is a measurable biological system

The gut microbiome is a diverse microbial community

The role of gut microbes depends on ecological context

Microbes convert fuel into compounds that influence health

What is produced depends on:

This is why microbiome assessment increasingly focuses on functional capacity and metabolic output — not just species detection.

It’s not enough to know which microbes are present you need to know what the ecosystem is doing

Key helpful functions of the gut microbiome

Metabolism

Immune regulation

Gut barrier function

Systemic signalling

The microbiome functions as part of human biology — not separate from it.

What shapes a person's gut microbiome

What happens when the microbiome is out of balance

How imbalances can affect the immune system and inflammation

Pro-inflammatory LPS (endotoxin)

Mucus layer damage when fibre is low

Lower butyrate and IPA-producing species

Defending against pathogens

What matters most in clinical interpretation

Key Takeaway

Fundamentals webinar

Microbiome research is no longer about detection, it’s about function

EARLY 2000S

2010’s

current

Microbial function significantly influences chronic conditions

Four core physiological functions influenced by the microbiome

Immune regulation

Gut barrier function

Metabolism

Systemic signalling

Simplified microbiome models are not sufficient for effective care

Key Takeaway

Microbiome research is no longer about detection, it’s about function

EARLY 2000S

2010’s

current

Early Microbiome Research

Current Microbiome Research

Core physiological functions influenced by the microbiome

Physiological Function Summary

Immune regulation

Barrier integrity

Metabolic signalling

Systemic signalling

The microbiome influences chronic disease through core physiological functions

What this looks like in practice

Clinical presentations

Clinical presentations

Clinical presentations 1,13

Did you know?

Simplified microbiome models are not sufficient for clinical practice

A clinically responsible framework therefore recognises several principles supported by microbiome research:

Key Takeaway

Microbial diversity protects against pathogens through colonisation resistance

Did you know?

Diet determines microbial outputs

The same microbes can produce different metabolites

Microbial metabolites shape immune function across the lifespan

Health outcomes depend on community cooperation, not individual organisms

Functional potential only becomes functional reality when the right conditions align

FUNCTIONAL POTENTIAL

The gut microbiome is
a measurable biological system

The gut microbiome is
a measurable biological system

Immune
regulation

Gut barrier
function

Systemic
signalling

Clinical presentations ^1,13

A comprehensive gut health test
built on all three

Validated sample preservation
protects the accuracy of every result

An ISO 15189 accredited laboratory has
processed over 100,000 metagenomes

Shotgun metagenomics
enables functional profiling

The Microba Community Profiler achieves  99% precision — peer-reviewed and benchmarked

Evidence-graded actions give practitioners
a clear basis for clinical conversations

Mucin degradation and intestinal
inflammation

What makes Microba’s
approach different

A considered integration of science,
evidence, and quality