Q: Bianca is in her mid thirties and has recently noticed several grey (gray) hairs after a henna application. She asks could henna be causing the grey hair?
A: In short it is unlikely. Henna is a dye that works by depositing onto the outside of hair. It is not known to affect the inner cortex where hair colour originates. It is also not known to affect the hair follicle. The usual colour effect as a result of henna on lightly coloured hair is within the yellow, orange and red region. If your hair is darker then the effect is much less noticeable.
Scientists are doing a lot of research into exactly what causes grey hair. It appears that it is hereditary and race has something to do with it. The average age of grey hair onset in White people is mid thirties, Asian* people start a little later in their late thirties and the latest onset is mid forties for Africans (Journal of Investigative Dermatology pg 13-21, 2005).
Additional reading - All the previous posts that I have done covering details from how henna works to the curl loosening theories - click here!
*The word Asian was substituted here for Oriental. I do not consider the word Oriental to be inappropriate/politically incorrect. One reader did consider it to be and Asian as the more appropriate word so it is now substituted. I did a little bit of research and found that the word Oriental is widely used in Britain and is not considered to be racist or culturally insensitve. I have even found that there are many Universities currently with Schools or Faculties of Oriental studies - This includes Oxford. I am happy to have an open discussion on this, feel free to give your input.