Not much you can do about that other than use hair dye.
It is called the genetics and aging combo.
They have dye just for men's facial hair. You might consider a copper deficiency, but if it's not all your hair turning white, that's probably not it -- pretty uncommon as well.
mostly white hair grow due to age,, but not only the old ones can have it even the children,,, even at you age 31....usually it is genetics.. did someone on you family have the same case? then if yes, then there is nothing we can do about it...it is the nature of life.. but if not? why not seek the doctors advice..
you cant stop it growing you can just control it maybe use wax strips or go have it done in a barber shop