Vitamins won't reduce hair loss at all, unless of course you have deficiencies in your body. Vitamins do however help the quality of your hair, so if it's a bit lifeless, maybe will make your hair appear a little bit thicker (by improving the texture etc.) but generally does not have any beneficial effect for hair loss specifically.
Minoxidil and/or anti-androgens like finasteride is everyone's best bet as it has been for the past 20+ years.