Knowledge of the gastrointestinal (GI) microbiome, including its metabolic potential, provides the opportunity for registered dietitian nutritionists (RDNs) to offer more personalized nutrition advice for our clients. The GI microbiome is the entire community of microbes, which includes bacteria that live within the GI tract. In GI conditions, an opportunity may exist to reduce symptom severity by manipulating the bacteria present in the gut. In metabolic conditions, individual features of the microbiome may explain why individuals respond differently to standardized nutritional interventions.