If you already have white hair, you can try one of the following natural remedies:
Massage your scalp with some onion juice to slow down the bleaching process. A study made at the University of Bradford show that enzymes present in onion juice can decompose hydrogen peroxide, preventing its accumulation in the hair follicles. Cut an onion finely as you can to get a paste or rub the scalp with half an onion.
According to research conducted at L.A. University, California, avocado has various medicinal properties due to the high content of fatty acids. It is rich also in minerals and vitamin E. Vitamin E is an extremely hydrating substance and a powerful antioxidant that prevents bleaching hair.
Cut an avocado in half, remove the core and put it in a bowl. Shred it and apply it directly to the scalp, leave it to act for 20 minutes, then wash your head normally.