Many diseases are associated with changes in the gut microbiome.
But an association does not tell us which came first.
The microbiome may influence processes involved in disease. At the same time, disease can change the microbiome.
How can the gut microbiome influence health?
Gut microorganisms interact continuously with the body.
They produce metabolites from food, interact with the immune system and influence the intestinal barrier. They are also involved in metabolic processes.
Changes in these interactions have been associated with gastrointestinal, metabolic, immune and neurological diseases.
In some cases, researchers are beginning to understand the biological mechanisms involved. In many others, the direction of the relationship remains uncertain.
How can disease change the microbiome?
Disease can change the conditions inside the gut.
Inflammation and changes in intestinal function can alter the environment in which gut microorganisms live.
Other changes often occur at the same time. A person may eat differently, exercise less or start taking medications. Antibiotics can have particularly strong effects on the gut microbiome.
This makes cause and effect difficult to separate.
Can we change the gut microbiome?
The microbiome is also influenced by factors that can change during life.
Diet and lifestyle are important examples. Researchers are also studying interventions including probiotics, prebiotics, postbiotics and faecal microbiota transplantation.
These approaches do not have the same evidence or clinical role. Their effects can also differ between individuals.
For healthy ageing, understanding these relationships is important. The gut microbiome is part of a dynamic system that interacts with our health, diet, lifestyle and environment throughout life.
