Brief Answer:
please provide more information and a photograph

Detailed Answer:
Hello Mr XXXXXXX
welcome to health care magic, I will definitely help you in best possible way but I will be requiring more information for better assessment like

Do you smoke or consume liquor?
Is there family history of early or premature graying of hairs?
what's your occupation?
If possible, please uplaod a photograph

Graying or white hairs in beard might be related to genetic as well as environmental factors.

Here I would advise you to follow these guidelines-

Have plenty of fresh fruits and vegetables
Avoid stress and anxiety, lead a healthy and cheerful life.
Multivitamin and calcium supplements are also advisable

Please write back to me with these details so that I will be able to tell you more precisely.
Awaiting your reply

Best wishes

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