Genetically modified maize. Conceptual image of a maize (Zea mays) cob with a grain highlighted in bright yellow. This represents modification of the genetics of the maize plant. The modification may create or strengthen desirable characteristics of the plant, such as resistance to disease. The use of genetically modified (GM) foods still remains controversial. Many foods are advertised as using GM-free products. Maize is one of the world's most important crops. It can be eaten as corn-on-the- cob, as popcorn, or ground into corn flour. It can be distilled to make a whisky, and extracts are used in cooking oil and margarine. Maize is a good source of potassium, vitamin A and fibre.