Consumers began noticing the disappearance of blue Froot Loops around 2012. And while there's no confirmed reason why the blue Froot Loops were discontinued, it has been suggested that it's because there is no blue fruits in the world.
Another reason is because they couldn't find a natural solution to get the blue color. In the UK, Froot Loops are purple, green and orange, due to the lack of natural colorings for yellow, red and blue, and are also larger in shape.
The "fruit flavored" circles touted by Toucan Sam are actually just "froot-blend"-flavored. All those colorful, sugary, circles of goodness taste exactly the same!
Kellogg’s introduced Froot Loops in September 1962. Originally, there were red, orange, and yellow loops, but green, purple, and blue were added during the 1990s.
Of interest, check out The Evolution of Froot Loops’ Toucan Sam: From 1960s Black and White to 2013 in 3D, featured on TrustCollective.com.