The trillions of microorganisms living in our gut are not fixed throughout life.
What we eat can help shape them.
Food provides nutrients not only for us, but also for the microorganisms living in our digestive system. Different dietary patterns can influence which microorganisms thrive and what substances they produce.
Fiber plays an especially important role.
Much of the fiber we eat is not fully digested in the small intestine. It reaches the large intestine, where gut bacteria can use it as a source of energy.
During this process, bacteria produce substances called short-chain fatty acids. These compounds help maintain the intestinal environment and interact with metabolic and immune processes throughout the body.
This makes the foods that provide fiber particularly important.
Vegetables, fruits, legumes, whole grains, nuts and seeds provide different types of fiber and plant compounds. Eating a variety of these foods gives gut microorganisms a wider range of nutrients to use.
The overall dietary pattern matters as well.
Mediterranean-style eating provides a good example. Research in older European adults found that following a Mediterranean diet for one year was associated with changes in the gut microbiome. These changes were also associated with lower inflammatory markers, better cognitive function and lower frailty.
This does not mean that everyone needs the same gut microbiome.
Microbiomes vary naturally between individuals. Age, medications, health conditions, environment and many other factors can influence them.
What we eat, however, is one factor we can change.
For healthy aging, the practical goal is therefore not to create a “perfect” microbiome. It is to provide our gut microorganisms with the nutritional environment that supports beneficial microbial functions.
Food variety matters — and so does what we feed our microbiome every day.
