Hello, Welcome to health care magic, I have read your query and understand your concern. Premature White hair or graying of hair could be related to stress, certain medications, usage of chemicals/dyes, genetics, nutrition/diet issues or thyroid or pituitary abnormality or Vitamin B12 deficiency. But it is not related to your bad habit means your masturbation. Masturbation is completely normal when it is done in privacy without hurting genitals. It is just like self sex and has nothing to do with good/bad health and which never causes weakness in the body.So,do not need to be worried about it. It would be better he should be go for blood investigations like routine blood counts, Thyroid profile, Growth hormone levels,Vitamin B12 levels, serum calcium to rule out above causes. Correction of the hormone would be required if some abnormality detected in blood tests. I would advise to use Pabatab-bz as it contains Para aminobenzoic acid, biotin and calcium panthotenate ,daily once for minimum 6 months. These supplements are necessary for hair and it helps in preventing premature graying of hair. You can also apply Altris gel which contains melitane which prevents and reverses graying of hair by stimulating melanin production. Avoid caffeine containing drinks and smoking if he does. Eats plenty of fresh fruits and spinach. Take protein rich diet like egg,pulses,fruits,green leafy vegetables are helpful. All these drugs are prescription based and should be taken under strict medical prescription of a doctor. So,better to consult dermatologist who will know about it. Hope this Will help you. Regards,