When you purchase chicken eggs at the market, they usually have white or brown shells. But some breeds of chicken produce blue or green eggs. The blue color is caused by insertion of a retrovirus into the chicken genome, which activates a gene involved in the production of blue eggs.

Are blue eggs safe to eat?

Specifically, it changes the chemistry of the eggshell so that it can take in biliverdin, a bile pigment, from the chicken's uterus. ... And not necessarily harmful; blue eggs are widely eaten and the Araucana, in particular, is a very popular exotic chicken breed.

Why are eggs blue or green?

Ameraucana birds have the pigment oocyanin deposited on the egg as it travels through the oviduct. This pigment permeates the egg shell resulting in the interior and exterior of the egg being the same blue color. ... In the case of an Olive Egger, a brown pigment overlays a blue egg shell resulting in a green egg.