Hi welcome to Health care magic forum.
Thanks for calling H.C.M.Forum.
You are 26 years old, You have grey hair of 20%, As you have assumed the main causes are nutrition and pollution.
Other causes are heridity,
anxiety,
stress and strain.
Diet must be rich in
proteins, iron, anti oxidants, and
vitamins. Green leafy vegetables, sea foods, have more iron and anti oxidants. pulses and nonvegetarian foods have more of proteins, and vitamins.
Anxiety ,stress and strain should be taken care of. Follow diversion procedures like
yoga,
meditation, reading books of your interest, and hearing music can improve your gray hair.
Heridity may not have a reply, but the above procedures can be usefull to some extent.
For further help you can consult at TRICHOLOGY clinics.
Wishing for a quick and complete recovery.
Best regards.