Please DO NOT take vitamins that are not designed for you. Its very silly and no the "extra" vitamins do not go straight to your hair, they hardly have a sat nav to get them there do they? You will just end up urinating them out and it will be a waste of your time and money. There are plenty of vitamins specifically designed for Skin,Hair and Nails ( please see link below) or talk to a nutritionist who will talk you through your diet and see if there is anything you can change. Ultimately nothing will make your hair grow more quickly, but there are things out there to help with general hair health. Hope this helps
http://www.hollandandbarrett.com/pages/product_detail.asp?pid=247&prodid=327&cid=30