Next time just tell people you take vitamins for your overall health, because like you said they would benefit there. People would think I was a junkie if they saw my vitamin cabinet, but yet i'm always getting compliments on my clear skin, natural nails, etc. I don't get sick often either.
I don't believe that you have to take tons of vits to get your hair to grow, but I do think that if you don't have a balanced diet, they are important anyway.