HOW HAIR GROWS

The hair follicle (also known as the hair root) is located under the scalp and must function properly to maintain healthy hair. The hair follicle is about 4 to 6 millimetres long. Each follicle produces one to four hair stalks, each of which is about 0.1 millimetres long. Thus, these hair stalks are very small.

Hair does not grow in individual strands, but develops from the scalp in groups of one to four and sometimes even five or six strands. The hair follicles are arranged in naturally occurring groups, called follicular groups.

About 90% of your hair is actively growing. Typically, hair grows at a rate of about 1.25 cm per month. The catagen phase is a transitional phase between the growth and resting phases. During this phase, the hair follicle withdraws and detaches from the hypodermis (from where it receives nutrients). The root of the hair disappears and the end of the root turns into a knot-like shape.

About 1 per cent of hair is in the catagen phase. This phase usually lasts about one to two weeks. The rest of the hair is not actively growing and is in the resting phase, also known as the telogen phase. This phase lasts about three to five months with a healthy scalp.

People lose about 100 hairs a day. The presence of significantly more hair on the brush, in the sink in the bath can be the first sign of excessive hair loss.

The stages of hair growth are as follows:

1. Each follicle contains a hair root, which is made up of protein cells.
2. As the blood circulates through the body, it delivers oxygen and nutrients to the protein cells, which need to multiply.
3. When the protein cells multiply, they build hair that pushes through the skin.
4. As the hair grows out of the skin, it passes through an oil gland. This lubricates the hair with oil, which must remain soft and shiny.
5. By the time the hair is long enough to pass through the skin, it is dead. As new hair grows underneath, it pushes the dead hair out of the skin. The hair then falls out or is shed.

Factors affecting hair growth

Everyone's hair is different and many factors can affect how quickly it grows.

These include:

- Genetics: A person's genes will dictate how fast their hair will grow.

- Gender: Male hair grows faster than female hair.

- Age: Hair grows fastest between the ages of 15 and 30, before slowing down. Some follicles stop working - completely - when people get older. This is why some people have thinner hair or go bald.

- Nutrition: Good nutrition is essential for growing and maintaining healthy hair.