I know this seems morbid, but bacteria plays a part, candida invades our system, as we live and that is the problem

As the cells die, bacteria within the body begin breaking them down. Enzymes in the pancreas cause the organ to digest itself. The body soon takes on a gruesome appearance and smell. Decomposing tissue emits a green substance, as well as gasses such as methane and hydrogen sulfide. The lungs expel fluid through the mouth and nose.