Understanding Melanin : Pigmentation, Benefits, and Effects

Melanin is a type of pigment present in our skin that produces pigmentation in our skin, eyes, and hair. Each person has a different amount of melanin in their skin, which is usually determined by their genetics and other factors. Scientists have identified three main types of melanin in humans, including: Eumelanin, Neuromelanin, and Pheomelanin.^(1, 2, 3)

Eumelanin and pheomelanin are pigments present in the epidermis, which is one of the skin’s layers, while neuromelanin is a pigment found in the brain that gives color to certain brain structures.^(4, 5, 6) This is why when we talk about the skin, we usually refer to just two types of melanin – eumelanin and pheomelanin. However, neuromelanin is of great interest to researchers as it is believed to have a connection to Parkinson’s disease.

The pigment eumelanin is linked with darker tones like black and brown, while pheomelanin is associated with alternate colors such as yellow and red.^{(7, 8, 9, 10)}

The production of melanin begins in a type of large cells known as melanocytes, which are found all over the body. Melanocytes are known to produce melanosomes, which are the site where eumelanin and pheomelanin are synthesized. These are then distributed to other cells, including skin cells known as keratinocytes.^(11, 12)

The amount of melanin in your body is largely determined by genetics, which in turn determines the color of your hair, eyes, and skin. However, there are also several other factors that influence the production of melanin, including hormones, age, exposure to ultraviolet (UV) light, inflammation, and certain types of skin pigment disorders.⁽¹³⁾

Apart from lending pigmentation in humans and animals, melanin has a critical biological role to play as it provides protection against damage caused by sun rays.⁽¹⁴⁾

Melanin provides protection against UV light by keeping the cells of the epidermis safe. The epidermis is the outermost layer of the skin. Melanin is able to protect the epidermis from all forms of UV light, including UVA, UVB, and UVC, and even blue light. This is done by absorbing the UV light before it causes any damage to the DNA of the skin cells.⁽¹⁵⁾

Melanin acts as an antioxidant by scavenging reactive oxygen species. This is why melanin is sometimes also known as reactive oxygen species (ROS) scavenger. If the body’s antioxidants do not intervene, these ROS can cause oxidative stress, which can lead to substantial cellular damage.^(16, 17)

Scientists believe that there are various other mechanisms of action for melanin inside the body, including protecting the intestines, liver, and even the immune system.⁽¹⁸⁾ However, as research is limited on these potential benefits, this is why pigmentation and photoprotection are known to be the main benefits of melanin in humans.

There are so many variations in our skin, eye, and hair color that it is natural to assume we all have very different levels of melanin in our bodies. However, it surprises people to learn that almost all humans have nearly the same number of melanocytes in the body. What is different, though, is that people with, darker skin tones have a higher number of melanosomes that are also larger in size and are more pigmented than the ones in people with lighter skin tones.

Melanosomes are also known to show certain distribution patterns depending on the exact skin color. These are the differences that contribute to the wide range of skin tones and colors that we observe in human beings.⁽¹⁹⁾

While genetics typically determines the exact amount of melanin in your skin, eyes, and hair, but there can be certain medical conditions that develop when we don’t have enough melanin. These include:

• Albinism: Albinism is a rare hereditary condition that occurs when the body fails to produce a sufficient amount of melanin. This usually happens due to a reduced number of melanocytes or decreased production of melanin from the melanosomes. There are several types of albinism that exist, but most of them cause a moderate to severe lack of pigmentation in the skin, eyes, and hair.^(20, 21)
• Vitiligo: Vitiligo is a type of autoimmune condition that happens when the body fails to produce a sufficient number of melanocytes. This leads to a lack of pigment that starts showing up on the skin or hair as white patches. Vitiligo is estimated to affect nearly one to two percent of people around the world.^(22, 23)

It is possible to increase melanin production through tanning. However, tanning can be dangerous as it can cause skin damage and also increase the risk of skin cancer. Remember that when the skin is exposed to sun rays, harmful UV rays start penetrating through the skin and can cause damage to the DNA of the skin cells.⁽²⁴⁾ As a response to this cellular damage, the body starts producing more melanin in an attempt to protect the cells. This increase in melanin is what creates the well-known ‘tan’ look on the skin.

However, when the skin starts to tan, this is the first indication that cellular damage has already taken place. At the same time, the amount of increased melanin produced through tanning, regardless of whether it is caused by the sun or any other exposure to UV light, is not enough to be able to protect the skin cells from suffering more damage. Over a period of time, this type of cellular damage is known to be a potential cause of skin cancer.^{(25, 26, 27)}

Melanin is an important pigment in the body that gives color to skin, eyes, and hair in humans and animals. Apart from lending pigmentation to our cells, melanin plays a very important role in absorbing the harmful UV rays from the sun and protecting us against cellular damage caused by this type of exposure to UV light.

The levels of melanin in the body are determined by your genetics, but they can be influenced by external factors like excessive sun exposure, hormones, or sometimes your age. It is best to avoid overexposure to UV rays in order to ensure that the pigment melanin continues to protect your skin cells in a normal manner.

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