Glossary · Microbiota
Eubiosis
In one sentence
Eubiosis is the state in which the microbiota is stable, diverse and compatible with the host's health. It is the opposite of dysbiosis, although neither term has an agreed operational definition.
Also known as: normobiosis · balanced microbiota · healthy gut microbiome
What is eubiosis?
The term comes from the Greek eu (good) and bios (life). It describes a microbiota in balance with its host: the community carries out its metabolic and immune functions, resists colonisation by opportunistic organisms and recovers after a temporary disturbance such as a course of antibiotics.
It is the counterpart of dysbiosis. Yet neither concept has a consensus definition that can be applied directly. A 2024 review in Gut by Van Hul, Cani, El-Omar and colleagues, What defines a healthy gut microbiome?, concludes that there is no universally accepted definition of a healthy gut microbiome and that individual variation, diet and lifestyle all need to be taken into account.
How it is assessed
Eubiosis is not measured with a single number. It is inferred from several features that research associates with health:
- Adequate diversity, expressed as alpha and beta diversity.
- Stability over time and resilience after disturbance.
- The presence of groups with known functions, such as butyrate producers or bacteria involved in mucus metabolism.
- No relevant pathogens or overgrowth.
The relative abundance of each group is compared with reference ranges from healthy populations. These ranges can differ between laboratories and methods, and a value outside the range does not in itself indicate disease.
Example
A dietitian working in a clinical team reviews a follow-up report three months after a dietary change prescribed by the patient’s doctor. Diversity has increased and the butyrate-production profile now sits within the reference range. The team reads this as a favourable shift in the microbiota, without crediting it alone for the improvement in symptoms, which is assessed clinically.
Limits of the concept
Eubiosis is a useful word for communication, but it has limits. What is balanced for one person may not be for another, and composition changes with age, pregnancy and diet. Most “healthy” traits also come from association studies. Messages about a “perfect microbiome” are best avoided in favour of profiles that are compatible with health.
Eubiosis at Xenogene
Xenogene’s Essential Microbiota analysis assesses, quantitatively and qualitatively, 150 gut microorganisms of clinical relevance using Nanopore NGS sequencing. The report covers relative abundance, alpha and beta diversity (compared with a healthy population), dysbiosis indices and functional profiles including butyrate, mucus, serotonin and GABA. It is designed as a first assessment and for follow-up after an intervention, always on prescription and interpreted by the requesting professional.
Frequently asked questions
How do I know if my gut microbiome is healthy?
No single value confirms it. Diversity, stability and the presence of groups with known functions are usually assessed, but always alongside the clinical picture. In practice, the absence of digestive symptoms or disease remains the most widely used criterion.
Is there an ideal gut microbiome?
Recent reviews suggest probably not. Healthy people have very different compositions, shaped by diet, environment, age and genetics. It is more accurate to talk about traits associated with health than about one ideal profile.
Related terms
- Dysbiosis
Dysbiosis is a change in the composition or function of the microbiota away from what is considered compatible with health: loss of diversity, loss of beneficial microbes or overgrowth of others.
- Microbiota
The microbiota is the community of living microorganisms (bacteria, archaea, fungi, protozoa) that inhabits a specific site of the body, such as the gut, mouth, skin or vagina.
- Alpha and beta diversity
Alpha diversity measures the variety of microorganisms within a single sample (how many types and how evenly spread); beta diversity measures how different two or more samples are from each other.
- Relative abundance
Relative abundance is the share of a microorganism in the total detected in a sample, usually given as a percentage. It reflects its weight within the community, not its absolute quantity.
Educational content for healthcare professionals and the general public. It does not replace assessment by a healthcare professional: ordering and interpreting any test is the responsibility of the requesting clinician.
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