In 2006 it was announced that Nestlé were removing all artificial colourings from Smarties in the United Kingdom, owing to consumer concerns about the effect of chemical dyes on children's health.[10] Nestlé decided to replace all synthetic dyes with natural ones, but, unable to source a natural blue dye, removed blue Smarties from circulation (which led to the common misbelief that blue Smarties triggered hyperactivity in some children) and replaced them with white ones.[11] White Smarties were replaced by blue Smarties in the United Kingdom in February 2008, using a natural blue dye derived from the cyanobacterium spirulina.[12]
Artificial colouring was removed from Smarties on the Canadian market in March 2009. The new range included all the colours except blue. Blue Smarties were re-added in May 2010.[13]