Did you know that your skin is the largest organ in your body – and one that’s constantly replenishing itself?

It’s made up of four layers. New cells are created at the base layer and move up through the four layers over a period of 25-30 days. When they reach the surface, we shed the cells.

This never stops: each day, you shed thousands of microscopic flakes of skin known as ‘squames’. Over a year, these add up to around 4kg in total!

As an area of skin, the scalp is a bit different. It produces the most visible hairs – you’d find between 100,000 – 150,000 if you counted them. And if you were to measure shoulder-length hair as a single strand, it would stretch up to 30km!

This warm, sheltered environment made up of loose skin flakes and hair makes an ideal home for micro-organisms. And here’s where the scalp differs again: it has a natural defence system against these organisms called sebum, a lightly greasy substance.

However, one organism, Malassezia, has adapted to live off sebum. It’s as a consequence of this that it causes the shedding process to speed up – as quickly as seven days in extreme cases. When this happens, the small flakes clump together and we see them as the flakes associated with dandruff.