Every year millions of people undergo treatment for major depressive disorder (MDD) including taking the drug escitalopram, which has been found to improve abnormal blood metabolism. But how does escitalopram affect the gut microbiota? In a recent study, researchers discovered that escitalopram upregulates certain amino acids that MDD can deplete, while also downregulating fatty acids typically found in excess in patients with MDD. Interestingly, escitalopram treatment also impacts the gut microbiota, reducing microbial richness and function. Using machine learning, the team found a relationship between the initial richness of gut microbiota and clinical remission from MDD by week 12. Furthermore, the researchers demonstrated the ability to predict clinical remission based on the presence of particular genes known as sporulation genes , rather than based on the gut microbiota composition before antidepressant treatment. Two limitations of this study include a lack of a longitudinal control group and the possibility of unidentified confounding factors. Overall, the findings could lead to better treatment strategies for MDD that consider the interplay between the gut microbiota and blood metabolites making a promising move toward personalized treatment strategies for depression.