I started off as a biochem major, thinking I had to be a bio major to get into MD school... ended up switching to public health and it was the best decision ever. As someone previously said, it's nice to have a major that can land you a job if med school doesn't work out, you can work in the county health department, go into epidemiology, or work in hospital admin with a public health degree... if med school does work out, you know a lot about public health and preventative health/disease epidemiology that I feel is relatively useful... it's nice to know about the system that you're ultimately going to be practicing in and what you're going to be getting into... from the perspective of a medical school applicant, not many students can say that they know much about the system... in my interviews I was able to talk about the healthcare system very in-depth (some of the MMI questions ask about health care issues and public health issues), and I think that was another advantage of being a ph major