Your gut microbiome changes throughout life.
But can it tell you anything about how healthily you are ageing?
Research suggests that it can provide useful information. But it cannot yet predict how long you will live.
A study of more than 9,000 people found that gut microbiomes became increasingly individual from mid-to-late adulthood.
After about age 80, this pattern differed according to health.
Healthier older people continued to develop more individual microbiomes. This was much less apparent in people with poorer health.
The researchers also found links between microbiome patterns and microbial metabolites in the blood.
What About Survival?
The study followed 706 older men for about four years.
Among the 256 men aged 85 years and older, lower microbiome uniqueness was associated with shorter survival.
Higher levels of Bacteroides were also associated with higher mortality in the older male cohort.
These are associations. They do not show that the microbiome determined how long these men lived.
Which Comes First: Health or the Microbiome?
This is one of the main questions in microbiome and longevity research.
The microbiome may influence health through its interaction with metabolism, immunity and the intestinal barrier.
But health also influences the microbiome.
Disease can change what we eat and how active we are. Medications and antibiotics can alter the gut microbiome directly. Age, lifestyle and environment also influence its composition.
A microbiome associated with poorer survival may therefore partly reflect poorer health that was already present.
Current research cannot always separate these effects.
What Does This Mean for Longevity?
Your gut microbiome may provide information about how your body is ageing.
But a microbiome test is not a test of life expectancy.
Its value lies in understanding your individual microbiome together with your health, diet, medications and lifestyle.
This information may help identify areas where changes in diet and lifestyle could support a healthier microbiome.
Research is now moving towards more personalized approaches. The aim is to understand which microbiome patterns and interventions are relevant for each person rather than define one ideal microbiome for everyone.
