Vitamins and supplements for dry, weak and thin hair

[hair_fighter]

Im suffering hairloss from the past 2 yrs and im 21 now. My hair looks very weak, dry and thin (but not worst enough to show any scalp). i also have some white hairs. i doubt that the weak and thin hairs are due to nutritional deficiency and unbalanced diet. i have pretty amount of thick hair at 18 but it is worst now, also my hair grows very slower now when compared to growth at my 18. when im 18 my hair grows really faster in 1 month after my haircut such that it used to cover my eyes but now even after 3 months of haircut my hair just grows a inch or longer. so guys i really need some info on essential vitamins and supplements such that my hair grows thicker and faster. Any suggestions are really appreciated.

Thanks.