Each hair is attached to the scalp via a follicle. There are between 100,000 and 350,000 hair follicles on the human scalp. Each follicle grows its hair for an average of 1000 days (three years) and then rests for a period of around 100 days (three months) before being shed and a new hair begins to grow. This pattern of active growth followed by the resting period varies significantly from person to person and is influenced by age, diet and our state of health.
Hair is primarily made of a protein called keratin that also makes nails and forms the outer protective layer of skin. Each hair consists of three layers:
1. The cuticle – the outer layer, thin and colourless. It acts as the protective layer.
2. The cortex which contains melanin, which is responsible for hair colour.
3. The medulla, the innermost layer which reflects light.
Did you know…
…Whether your hair is straight or curly depends on the shape of the cortex. On average, blondes have more hair and redheads have the least.
The length of hair that you are able to grow is controlled by the duration of the growing phase, which varies between individuals. We all lose some hair naturally each day when we brush, comb or wash it and as long as new hairs are being produced at the same rate as those falling out, there will be no difference in hair volume. However if the rate of shedding exceeds production the net result is hair loss or thinning.
A variety of factors can alter the normal hair growth cycle and cause temporary or permanent hair loss including medication, chemotherapy, exposure to chemicals, hormonal factors, thyroid disease, stress or nutritional factors.
We shed hair every day as part of our body’s natural process. Hair loss can happen at any time of life for any number of reasons. When hair loss becomes a concern, it is important to determine the cause before seeking out the appropriate treatment.
Potential non-dietary factors for hair loss include: