My hair was turning white but my age is 25

causes of white hair early appearance :
1. family history 
2. vitamin b12 deficiency
3. iron deficiency
4. calcium deficiency
5. smoking is related but not direct cause
What to do next :
1. visit  dermatology doctor to do the needed medical examnations and determine the treatment pathways 
2. taking good care of your hair health to avoid worsning the medical condition 
3. avoid smoking , using any chemical substance which will make your medical condition worse as well
4. using sunblocking and herbal products to protect your bread hair and usually its contain cinnamidopropyltrimonium
chloride
5. oral suppliment such as Methionine
6. you can also some dying hair product but try to use herbal and natural products as much as you can 
needed medical examnations :
1. clinical examnation by doctor 
2. blood and blood content test
3. vitamin b 12 , and calcuim check