Melanin – Types, Functions, Benefits and more

Have you ever wondered what gives colour to the skin? Why does skin tone differ for each individual?

Humans come in various colours including light and dark skin, black, white, brunette and blond hair, and green, blue, black, hazel, brown and amber eyes.

It’s incredible to realise that most of the colour is due to only one single class of pigments known as melanins.

What is Melanin?

Melanins are a class of compounds that primarily function as pigments. These pigments are made from an amino acid called tyrosine.

Melanin is responsible for the colour of the skin, hair and eyes. Melanin is a dark biochrome pigment also found in some internal membranes.

Melanocytes, cells present in the innermost layer of the skin and hair follicles, produce melanin pigments.

Melanin level in the skin depends on the extent of the skin’s exposure to the sun.

Melanin serves a dual function in the body. On the one hand, it produces a brownish pigment that protects the body from the effects of ultraviolet (UV) light from the sun.

These pigments can accumulate in concentrated forms that pose health risks.

Types of Melanin

Melanin exists in three forms in humans, namely, eumelanin, pheomelanin and neuromelanin.

Eumelanin

Eumelanin levels influence the appearance of hair colour. A high concentration of black or brown eumelanin results in darker hair, while a low concentration results in lighter hair colour.

Pheomelanin

Pheomelanin levels impact skin colour, rendering pink, red and yellow tones. Red hair results from an equal amount of pheomelanin and eumelanin.

Neuromelanin

Dark colour to certain parts of the brain is provided by neuromelanin.

According to research, the presence of this pigment helps prevent cell death in certain areas of the brain.

Neuromelanin deficiency can have an effect on Parkinson’s disease, a neurologic disorder.

Functions of melanin

Melanin performs several functions in the body through its various types. It contributes to the skin and hair pigmentation and also the photoprotection of the skin and eyes.

Pigmentation of the hair

The colour and pigmentation of the hair are influenced by the proportion of different melanin present.

• Blonde hair – Due to the presence of a little quantity of brown eumelanin and nil black eumelanin.
• Black and brown hair – Due to varying amounts of brown and black eumelanin pigments.
• Red hair – This is produced by an equal amount of eumelanin and pheomelanin.
• Strawberry blonde hair – It is as a result of brown eumelanin along with pheomelanin’s presence.

Pigmentation of the skin

Pigmentation of the skin can be ascribed to the accumulation of melanin-containing melanosomes in the basal layer of the epidermis.

Skin pigmentation varies based on two factors.

• Due to the ratio of eumelanin to pheomelanin
• Number of melanosomes in the melanocytes.

Pinkish skin makes up the lips, vagina, nipples and glans of the penis. Pheomelanin is responsible for this pink skin.

Protection of the eyes and skin from sunlight

Melanin not only functions by guarding the skin against photodamage, but it also protects the eyes.

Melanin is concentrated in the iris and choroid. This makes albinos and people with blue, grey or green eyes more prone to sun-related ocular problems.

The substance absorbs ultraviolet rays and redistributes them to the skin’s upper layers. It also shields the genetic material stored in the cells from harmful UV rays.

Benefits of melanin

The role of melanin in rendering colour to the skin, hair and eyes is widely known. They also function to provide other benefits.

Protection from UV light

Melanin absorbs and distributes the absorbed UV ray’s light energy. It protects one’s genetic material stored in nuclei from the rays.

This skin pigment prevents UV radiation from damaging DNA and potentially causing skin cancer.

Protection against reactive oxygen species

The antioxidant properties of melanin provide assurance against Reactive Oxygen Species (ROS). These are byproducts of the body’s cellular processes.

It is said that when ROS accumulates in cells, it can cause damage to the cells. ROS is associated with cancer, Diabetes and ageing.

Melanin has the ability to capture ROS that forms when UV light causes oxidative stress on the skin.

Skin disorders of melanin imbalance

The skin becomes dark when the body secretes excess melanin. Conditions like pregnancy, Addison’s disease and exposure to the sun has the ability to darken the skin,

The skin lightens when the body produces insufficient melanin.

Vitiligo 

Vitiligo is a chronic skin condition that causes pale white patches to appear on the skin.

It is caused by a lack of melanin in the skin. Vitiligo can affect any part of the skin, but it most commonly affects the face, neck, hands and skin creases.

Albinism 

Albinism is characterised by melanin deficiency or the absence of melanin entirely. This has an impact on skin tone and vision.

Albinism is a chronic condition that interferes with the production of melanin. It does not worsen over time.

Melasma

Melasma develops when the skin produces an abnormally large amount of melanin. Melasma stimulates an increase in melanin production, resulting in dark patches on the skin.

Pigment loss following skin damage 

Pigment loss occurs on the skin due to ulcers, burns, infections or blisters. It is difficult to replace or treat the infected part.

Hearing loss 

Melanin has been associated with hearing loss as It is found in the stria vascularis of the inner ear.

People with low melanin levels are more likely to have hearing problems.

Parkinson’s disease

Parkinson’s disease is characterised by selective degeneration of brain cells containing the dark-brown pigment neuromelanin, particularly in the substantia nigra region of the brain.

Parkinson’s disease is associated with a lack of neuromelanin in the brain.

How does melanin react to the sun?

Melanin protects the skin by shielding it from the sun. It is the body’s natural sunburn defence mechanism.

When the sun rays touch the skin, the body produces a hormone that binds to melanin-producing cells. This triggers them to secrete excess melanin for additional protection.

Melanin is found in the lower layer of the epidermis and darkens while it spreads to the upper layers.

Sunburns are as a result of UVB radiation, which burns the epidermis, the upper layers of skin.

Tans are due to UVA radiation. UVA rays penetrate the epidermis and move to the lower layers. It is here that they stimulate melanocytes to produce melanin.

Melanin is the brown pigment responsible for tanning that helps guard against the sun.

What affects melanin levels in the skin? 

Melanin levels are mostly determined by

• Genetics
• sun exposure
• Hormones and
• Age

Genetics is the predominant factor for the melanin levels in the skin.

When to see a doctor? 

Doctor consultation is recommended when new patches of discolouration appear on the skin and do not fade.

If a mole changes in size, shape or texture, it is also important to seek medical attention.

It is also advisable to consult a professional when the skin or hair loses its colour, which can signify vitiligo.

Conclusion

Melanins are pigments that are responsible for the colour of the eyes, hair and skin. Their levels also depend on the extent of skin’s exposure to the sun.

The major role of melanin is to shield the skin from the sun. One has to be aware of the impact of too much and too little melanin in the skin. When proper medical attention is provided, issues of melanin imbalance can be resolved.

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