Life is full of, or perhaps even defined by, choices and medicine is much the same. We have a certain degree of freedom to choose the way our body functions. Risk factors for heart disease can be categorized as modifiable (diet, lifestyle, exercise, mental outlook, etc.) and non-modifiable (age, sex, genetic predisposition, etc.). The role of the physician is to optimize those factors which can be changed. If it is understood that the state of the human condition is a function of our choices, it can be appreciated that our interaction with the environment, specifically the microbiome, affords us an opportunity to modify disease risk. As humans have developed over the course of evolutionary history in a symbiotic relationship with bacteria and other “invisible” life forms, there is no question that this relationship in particular is key.