What makes our hair the colour it is?

A pigment is a chemical that adds colour to something. Incidentally, the pigment that gives our skin its colour, is also responsible for giving our hair its colour. This pigment is called melanin.

Our hair consists of two parts: the shaft which is the part that grows out, and the root that keeps each hair anchored under the scalp. The root is surrounded by a pouch of tissue under the scalp called the hair follicle.

The hair follicle is what contains most of the nutrients for the hair to grow, the pigments that give the hair its colour, and also houses the biochemical reactions that makes hair fall out!

The melanin factor

There are two types of melanin pigments present in each hair follicle – eumelanin and pheomelanin. The amount of each of these pigments which blend together determines the colour of your hair.

Having a lot of pheomelanin gives you yellow or orange hair. Eumelanin darkens your hair; it has two subtypes: black and brown. Less brown eumelanin gives you blonde hair, while too little black eumelanin gives you grey hair.

The colour of hair we are born with is generally dependant on our genes. But the climate in the place we live in, the hair products we use, and other external factors play a role too, and so our hair colour may change in the course of our life time.

Why does hair turn grey?

Greying of hair occurs naturally as we age. This is usually because pigment cells in the hair follicles begin to die off. The brightness of our hair colour keeps reducing as this happens. When there is virtually no melanin left in the follicles, the hair turns somewhat colourless, and visibly white.

Each of us begin getting grey hairs at different ages. This is usually an inherited feature. Some begin growing grey hair in their twenties while others’ hair remains dark for a long time. External factors like pollution, climate and dietary deficiencies also play a role.

Scientists have also discovered that sometimes hair follicles produce small amounts of hydrogen peroxide. Accumulation of this chemical has a bleaching effect and contributes to hair losing its colour.

There is not enough scientific evidence supporting the popular claim that too much stress can turn hair grey. Surely that’s good news for the elders at home and school!

nandita.j@thehindu.co.in