Age brings with it many chronic conditions related to tissue decline and inflammation. The functions of our intestinal barrier, brain, and eyes can all be affected by changes in our gut microbiota which occur with ageing. However, we don’t yet know if age-related changes to the microbiome cause any of the observed changes in other tissues. To close this gap, researchers used fecal microbiota transfer (FMT) between mice of different ages. They found that transfer of gut microbiota from aged donor mice to young mice induced inflammation in the gut, brain and retina. Intestinal permeability was increased, and the brain showed microglial activation in these aged-to-young FMT recipients. The retinas of recipients also showed altered cytokine signalling and loss of a key protein important for normal vision, thus identifying a role for gut microbiota in regulating eye health. These effects could be reversed in aged mice receiving microbiota transfer from young donors, suggesting that young donor FMT may have therapeutic potential. This study only examined short term changes in mice, so longer term studies and research in humans is needed. However, these findings suggest that changes in the gut microbiota drive other age-related changes in the brain, eyes, and gut and that microbiota modulation may be a therapeutic target to slow such detrimental changes.