What Causes Greying Of Beard?

I am 37 year old.....sanjeev frm mumbai....my beard started greying when i was 27 yrs...although hair was black...its nw starting greaying past two years.....four years back i consulted a very known homeopathy doctor...he started giving medicine..that time i had 25% of my beard was grey including some grey strings on private parts like on testo....so wen he started i noticed on testo its turning black again .....bt after some time it stopped..and beard ratio increased 70%nw....someone told me that homeopathy first increaes the thing after it cures permanently.....is it true?and now i hve grey hair on eye bro,chest,40% of scalp hair...its very embarrasing.....i want to ask medical fraternity that u have researched on cancer aids ebola many more bt nt on this...its very common prblm for common people....can medicle science regenerate melanin and turns grey beard into black atleast in premature age......it ll be very helpful millions of pple who r victim of deprression......