color symbolism is rather culture-specific, and LOST has been quite a multi-cultural show. I'd like to think some colors keep coming back either because they've proven to be solid choices for simple and effective graphics (like use of b&w for the opening ) or because they have a specific meaning around the story line of certain characters. I doubt they have fixed meanings or msgs for the entirety of the show.

__________________
"Bear...? Is that you?"-- Hurley S03E4