The Science

What factors determine hair colour?

Before we look at what makes hair turn grey it’s worth reminding ourselves what make up our natural hair colour. The amount of melanin that is present in the pigmentation of hair follicles usually determines how light or dark your hair will be. More melanin means darker hair and less lighter hair. The level of melanin varies over time which causes hair colour to change and it is also possible to have hair follicles in different colours. There are two types of melanin pheomelanin and eumelanin. Pheomelanin colours the hair red whilst eumelanin gives degrees of brown or black depending on the level of concentration. For example a high concentration of brown eumelanin will make the hair brown whilst a low concentration of the same turns hair blond. When it comes to black eumelanin low amounts will give grey hair and high amounts black hair. The genetics of hair colours is still a grey area! Grey (or white) hair is actually clear due to lack of pigmentation and melanin and it is the way that light hits the hair that makes it seem grey. Albinos have white hair due to low amounts of melanin.

What causes grey hair?

There are many factors that may cause hair to turn grey and the most common factor is ageing. Whilst is it possible to get grey hair from as young as ten it typically occurs during the mid thirties for white people. It seems that genetics determine the age at which one will start getting grey hair. The change occurs when melanin stops being produced in the hair root and new hairs start to grow without pigment.  It is also possible that the following factors may cause premature grey hair; Smoking, deficiency of the vitamin B12 and thyroid deficiencies.