When your hair turns gray depends largely on genetics. If your parents turned silver early, you just might too. After gray shows up on your head -- between the ages of 25 and 50 for half the population -- there's little you can do to stop it.
Why You Gray
Graying occurs as you age and your hair follicles stop producing as much melanin, or color-producing cells. The hair from these pigment-free follicles shows up as whitish-gray instead of its normal blonde, black, red or brown. Nutritional deficiencies, particularly in protein, vitamin B-12 and certain amino acids, may also affect your melanin production. Thyroid imbalances and other medical conditions, such as anemia and vitiligo, can also be the cause. If you suspect you suffer from a medical condition, consult your doctor for a diagnosis and treatment.
Stop the Graying Process
Maintain a healthy and balanced diet to maximize your natural color as long as possible. After you start to gray, you can't go back. You can dye your hair to cover the silver, but you can't stop the natural aging process -- even if it comes too early to suit you. A pill is in development that may stop the breakdown of melanin production and prevent gray hair, but as of 2013, much research remained to be done on the product. Even if the pill were available, it could only prevent gray hair from developing -- not stop it after it appears.