The color of black hair is due to a pigment called melanin. Melanin production decreases with age, and hair slowly turns grey and finally white. Other than age, premature graying can occur in people due to hereditary reasons. If both your parents had premature graying, it will be highly likely that you will too. But sometimes it may be due to the type diet that you take, that creates grey hair. Black hair care must start with what you ingest.
Excessive intake of tea and coffee can cause premature graying as also junk and fried foods. You must watch your diet, so that it is filled with a lot of fruits, vegetables, nuts, whole grains and seeds. This is very important, not only for your skin and nails, but also to maintain your black hair. Ensure there is a lot of copper in your diet besides iron, zinc and iodine. Copper is found in sunflower seeds and cashews; iron is found in sunflower seeds and dried apricots; zinc in green leafy vegetables and iodine in carrots and bananas.
Vitamin B is especially important for hair. Brown rice and the Indian parboiled rice contain a lot of Vitamin B. So it's best to replace your white rice with brown or parboiled rice.
Here are some home remedies for black hair care, to prevent premature graying.
Put generous amounts of coconut oil every week. Leave it overnight if you can, and use a plastic wrap and towel to prevent staining your pillows. Coconut oil not only gives you thick hair, but also maintains your black hair as long as possible. Instead of coconut oil you can use coconut milk too.
You can add some amla (Indian gooseberry) powder or curry leaves into the coconut oil and boil it till the amla powder or the curry leaves burn and become black. Use this oil instead of plain coconut oil for black hair care. This is also a good remedy for gray hair as well.
One good home remedies for black hair care is to consume the curry leaves in curries, or even eat it on its own if you can. It'll prevent premature graying.
However the only way to treat already premature graying is to use henna. Take about 3-4 tablespoon of henna powder and add some amla powder. Make some concentrated tea solution and add to the mixture of powders. Squeeze half of a lemon and an egg. The amla can help hair grow and impart darkness to it. Concentrated tea may stain the hair a little, so that it gives a final darker sheen. Lemon helps in creating an even darker color to the hair for whatever reason. The egg has a nutrient that nourishes it. Add enough water to make a thick paste.
To apply henna, start from the crown. Take a tuft of hair, apply henna and twist that portion into a little bun. Now each time take a tuft, apply henna and twist it around the bun on the top of the crown. Continue till all the hair is covered. Leave henna for at least one and the half hours to two hours. Now wash off with water. And, shampoo with mild shampoo to get rid of the egg smell. If you are using henna without the egg, shampoo before using henna, and do not shampoo after that.
Even though there is hardly any ingredient to change gray hair into black, it's more important to maintain your remaining black hair as described above. So try one or all the home remedies for black hair care given above.