Your gut microbiome does much more than contain different microorganisms.
Gut microorganisms produce and transform many substances. These are known as microbial metabolites. They are one of the main ways the microbiome communicates with the body.
Some are produced when bacteria process components of food.
Short-chain fatty acids, for example, are produced when certain gut bacteria ferment dietary fibre. They can support the intestinal barrier and interact with immune and metabolic pathways.
Gut microorganisms also produce metabolites from tryptophan, an amino acid found in food. These substances can interact with the intestinal barrier, immune system and other biological pathways.
Other microbial products may have less favourable effects.
Lipopolysaccharide (LPS) is a component of certain bacteria. Increased exposure to LPS can stimulate inflammatory responses. Gut bacteria can also modify bile acids, producing secondary bile acids with effects on metabolism and cell signalling.
Why does this matter as we age?
The gut microbiome changes throughout life. Its metabolic activity can change too.
Research suggests that age-related microbiome changes may be accompanied by lower production of some beneficial metabolites and greater exposure to potentially harmful microbial products.
These substances may interact with several processes involved in ageing. They include immune regulation, inflammation, metabolism and mitochondrial function.
This helps explain why identifying which bacteria are present provides only part of the information about the microbiome.
What gut microorganisms produce may be just as important as which microorganisms are present.
Scientists are therefore increasingly studying microbial function together with microbiome composition.
Understanding these metabolites may eventually provide a more precise picture of how the gut microbiome interacts with the body during healthy ageing.
