Hello, I am 27 Male Indian. My beard is getting white, it started in Feb 2015 and i have 60 white hair..the problem is not genetic, yeah i smoke 5 cigarette a day, I drink at weekends, I never done drugs in my life. I am fully fit, no chronic problem but under weight 48kg (5'5'' height_165cm) I regularly have a balanced diet_all three meals but no milk, fruits & juices. I have a stressful life plus I think a lot. How to prevent white hair in my beard plus i want the white hair to turn to black.

PS: Head region having 50% white hair, it started in 2008.