Why Hair Turns Grey: Causes, Melanin and Prevention

In salon conversations and everyday accounts alike, the appearance of the first white strand often prompts curiosity and plenty of questions. In 2026, despite wider access to scientific information, people still commonly wonder what determines when hair starts to turn grey, whether hair colour affects the process, and how far this is simply a natural sign of ageing that differs from one person to another.

What causes grey hair and what is the role of melanin?

Whether hair is blonde, red, brown or black, its colour relies on melanin, the same pigment responsible for colouring the skin and eyes. This substance is made by melanocytes, cells located in the hair follicles, where each strand forms and grows over the years.

As these melanocytes begin to malfunction or disappear, pigment levels fall, causing hair to grow lighter, grey or entirely white. This is regarded as a physiological process, much like the development of wrinkles, and is not necessarily linked to illness, although very rapid changes may warrant medical assessment.

Watch a video on Dr Laura Aiello's YouTube channel explaining why hair turns white:

Does natural hair colour make hair turn grey earlier?

From a biological perspective, hair colour does not dictate the age at which strands will lose their pigment. The reduction in melanin production happens across every hair type; the difference lies in visual contrast, as a white strand is far more noticeable against black hair than against naturally blonde hair.

Chemical treatments, including bleaching, colouring and harsh straightening procedures, can leave hair duller or more brittle, but they are not regarded as a direct cause of greying. However, as hair grows, they may make grey roots more apparent, creating the impression that the hair turned white “suddenly”.

When does hair start to turn grey, and which factors play a part?

The average age at which white hairs first appear differs according to ethnic background, although individual variation remains substantial. In general, people of European ancestry tend to notice grey hair in their early thirties, Asian people towards their late thirties, and people of African ancestry at around 40.

Beyond population averages, other factors may bring forward or speed up greying. Among the most closely studied, several stand out because of how frequently they appear in research:

• Family genetics: a history of early white hair in parents and grandparents often recurs in their descendants.
• Chronic stress: this may affect follicle stem cells and encourage pigment loss.
• Nutritional deficiencies: low intake of B vitamins, iron or copper may affect hair health.
• Smoking and pollutants: these are associated with premature skin ageing and, in some studies, with a greater number of white hairs.
• Autoimmune diseases: certain conditions may directly interfere with hair pigmentation.

Can grey hair be prevented or reversed safely?

As of 2026, there is no proven, safe and widely effective method of permanently reversing grey hair in healthy people. Most available options are cosmetic, such as permanent dyes, semi-permanent colourants and temporary sprays, which merely conceal pigment loss.

On the other hand, looking after overall health helps the body function in a more balanced way, including the hair follicles. A varied diet, sufficient sleep, stress management, regular physical activity and avoiding smoking do not guarantee that white hairs can be prevented, but they support a slower, more predictable pattern of hair ageing, making grey hair a natural and less concerning marker of time passing.