Everyone has the same number of melanocytes, but some people make more melanin than others. If those cells make just a little bit of melanin, your hair, skin and the iris of your eyes can be very light. If your cells make more, then your hair, skin, and eyes will be darker.
The amount of melanin your body makes depends on your genes. If your parents have a lot or a little skin pigment, you’ll probably look like them.
How Melanin Reacts to the Sun
When you're in the sun, your body makes more melanin. It may help protect the body from harmful ultraviolet (UV) rays.
But it isn't enough to keep you safe from the sun. Your skin is already damaged if you’re sunburned or your skin has turned slightly darker. That's why it's important to always cover up and wear sunscreen.
Studies show people with darker skin get fewer cases of skin cancer than people with lighter skin. More research is needed to know if this is because of the amount of melanin in their skin.
Types of Melanin
People have three types:
- Eumelanin makes mostly dark colors in hair, eyes, and skin. There are two types of eumelanin: brown and black. Black and brown hair come from different mixes of black and brown eumelanin. Blonde hair happens when there’s a small amount of brown eumelanin and no black eumelanin.
- Pheomelanin colors the pinkish parts of your body like the lips and nipples. You get red hair when you have the same amount of pheomelanin and eumelanin. Strawberry blonde hair happens when you have brown eumelanin and pheomelanin.
- Neuromelanin Controls the colors of neurons. It isn't involved with the coloring of things you see.
Melanocytes make eumelanin and pheomelanin. Neuromelanin is found in the brain.
Disorders Related to Melanin
Issues with melanin are linked to several skin pigment disorders.
Albinism. This rare disorder results from very little melanin. People with albinism have white hair, blue eyes, and pale skin, and may have vision problems. They should wear sun protection to avoid sun damage. There is no treatment.
Melasma. People with melasma have brownish patches on their face. Researchers think it’s caused by hormones, birth control pills, and exposure to the sun. Prescription creams can lighten melasma, and sunscreens can keep it from getting worse. Laser treatment and chemical peels might also help.
Vitiligo. When you lose melanocytes, you get smooth, white patches on your skin. There's no cure, but treatment includes dyes, UV light therapy, light-sensitive medicines, corticosteroid creams, and surgery.
Pigment loss after skin damage. Sometimes after your skin is burned, blistered, or infected, your body can’t replace melanin in the area that is damaged. You won’t need treatment. You can cover the area with makeup if it bothers you.
Parkinson's disease . In Parkinson’s disease, neuromelanin in your brain drops as brain cells in an area called the substantia nigra die. Normally, the amount of neuromelanin in the brain increases as we get older.