As we grow older, our gut microbiota enters a period of increased volatility and reduced functional capacity. This contrasts with the relative stability of our gut microbiome in the early to middle years of our lives, according to a December 2022 report in Cambridge Core of Cambridge University Press (The Study).
The Study attributes these changes to biological and environmental factors as we age. These include the gradual deterioration of our immune system (immunosenescence), altered physiology in the gastrointestinal tract, age-related diseases, and increased exposure to medication and altered diet.
Clinical trials and research referenced in The Study show significant shifts in the abundance of certain bacteria strains in our gut such as Bacteroides, Faecalibacterium, Lachnospiraceae, and Akkermansia. Some studies have shown increases in these strains while others have shown decreases.
However, studies of fecal microbiome among centenarians across cultures (Italy and South Korea), consistently demonstrated an increase in Akkermansia muciniphila, Collinsella, Clostridium, and Christensenellaceae; and a decrease of Faecalibacterium and Prevotella. This suggests these strains contribute to health maintenance during aging.
As far as mental health maintenance, aging can lead to a decline in neuronal volume, changes in our neurotransmitter levels such as dopamine, serotonin and gamma-aminobutyric acid (GABA).