Fungal diseases are common place in plants and animals
In such diseases, the fungi are actively growing on and invading the body of their hosts. There is another means by which fungi can cause harm without invading our bodies. When fungi grow on a living organism or on stored food material that we consume, they may produce harmful metabolites that diffuses into their food. It is believed that fungi evolved these metabolites as a means of protecting their food supply by preventing other organisms from eating it.