this has been discussed at least a thousand times.
it comes down to what you do that stands out, ie they would take the biochem major that published his protein research over a mediocre theater major, or the theater major who worked on broadway over the mediocre biochem major.
that being said, it wouldn't surprise me if having an unusual major with good grades in core science classes puts you ahead. half or more of med school classes are well-to-do kids who chugged along the premed game from the start of college. it's refreshing to see somebody who tried something different and it's unique to be good at both hardcore science and something completely unrelated in the humanities.