An enormous community of bacteria and other microorganisms lives in our gut. We call it the gut microbiota and, just like us, it doesn't stay the same throughout life.
But what happens when we age? And most importantly: can what we eat influence this change?
The microbiota does not have a fixed age
As we age, the composition and functions of the microbiota can change. In the elderly, especially when frailty, changes in diet or lifestyle are present, some studies observe less microbial diversity and a reduction in microorganisms involved in the production of useful metabolites.
However, this does not mean that there is a single “young microbiota” to preserve. The differences between individuals are enormous, and research is still trying to understand which characteristics are truly indicative of healthier aging.
What does what we eat have to do with it?
A lot.
A portion of the fiber we eat reaches the intestine without being completely digested by us. Here it becomes a substrate for certain microorganisms, which can transform it producing molecules such as short-chain fatty acids, including butyrate.
And it's not just fiber. Polyphenols, present in numerous plant foods, also enter into a complex relationship with the microbiota.
This is one of the reasons why there is so much interest today in studying the entire dietary pattern, instead of looking for the single "superfood."
What about the Mediterranean diet?
This is where the story gets particularly interesting.
Vegetables, legumes, whole grains, fruit, nuts, and extra virgin olive oil provide a combination of fiber and bioactive compounds that interact with the gut ecosystem.
Recent reviews suggest that greater adherence to the Mediterranean diet may be associated with favorable changes in the microbiota and its functions, even in older people. But studies do not yet produce completely uniform results: analysis techniques, populations, and individual microbiota can vary greatly from one study to another.
And perhaps it is precisely this complexity that makes it so fascinating.
We are not simply nourishing ourselves. A part of what we eat feeds an ecosystem that lives with us — and changes with us.
Scientific note: Ticinesi A. et al., Aging Clinical and Experimental Research, 2024; Simbirtseva K.Y. & O’Toole P.W., Annual Review of Medicine, 2025; Khavandegar A. et al., BMC Medical Genomics, 2024.