I am an Epidemiologist with an MPH. It is my understanding that epi shows schools that you are interested in research. So if you are going to a strong research school, then go for it. But to be honest, I think they would prefer it if you took a hard science instead. Epi is very PUBLIC HEALTH and there is a great divide between the medical and public health worlds. many MDs don't understand the importance of population based health research. If its an interest of yours then pursue it, but Id recommend taking something that will make the adcomm drool instead.
Also, a note, most medical schools offer first or second year students a quick half semester overview of Epi. Not sufficient but at least you can get your bearings then?
