The word “dysbiosis” is increasingly used in microbiome reports and health information.
It describes changes in the gut microbiome that are considered unfavorable or out of balance. But the term is broad, and its exact meaning can vary.
Why is dysbiosis difficult to define?
Gut microbiomes differ naturally between people. They are influenced by age, diet, lifestyle, health, medications and environment.
Because this natural variation is so large, the boundary between normal variation and a potentially important change can be difficult to establish.
Having more of some bacteria and fewer of others does not automatically mean that the gut microbiome is unhealthy.
What happens to the microbiome as we age?
The gut microbiome changes throughout life.
Studies have found different microbial patterns in people experiencing healthy ageing, frailty and chronic disease.
But finding a difference does not tell us what caused it.
Changes in the microbiome may influence health. Disease itself can also change the microbiome. Diet, medications and lifestyle can affect both.
Understanding the direction of these relationships remains an important challenge in microbiome research.
What does a finding of dysbiosis actually tell you?
The word alone tells us relatively little.
Microbiome findings need to be considered together with gut health and the person’s overall health. Age, diet, medications and lifestyle also matter.
Researchers can examine which microorganisms are present and their relative proportions. They can also study microbial diversity and function.
This broader information can help us understand how the microbiome relates to health and ageing.
For longevity medicine, microbiome results are most useful when they are interpreted in the context of the individual, rather than from the presence or absence of particular bacteria alone.
