“…Environmental factors, such as UV light ( Trueb, 2006 ), smoking ( Mosley and Gibbs, 1996 ) and oxidative stress ( Shi et al, 2014 ; Wood et al, 2009 ; Kamenisch and Berneburg, 2009 ) might also contribute to premature hair greying, possibly through an increase in intracellular reactive oxygen species. Nutritional deficiencies in trace elements ( Fatemi Naieni et al, 2012 ), including vitamin D3 ( Bhat et al, 2013 ), vitamin B12 (such as in pernicious anaemia) and copper (such as in Menkes disease) can also lead to hair greying. These conditions are thought to reflect deficiencies in the pigmentation pathway rather than loss of melanocytes, such that colour can be restored with nutritional supplementation ( Heath and Sidbury, 2006 ).…”