Hi Premature greying of hair is usually heriditary stress and smoking may accelerate the greying. Eat plenty of fruits and vegetables and drink plenty of water. Avoid junk foods. Sleep early and avoid smoking. Thyroid dysfunction and severe Vit B 12 deficiency can also cause greying. Please get them tested. PABA containing multi vitamin supplements as well as Melitaine containing serums seem to arrest further greying. Please contact a dermatologist who can prescribe the appropriate hair care products