(Reuters) -A U.S. government report on the health of American children cited scientific studies that did not exist to support its conclusions, according to a media report and some of the purported study authors on Thursday. The report produced by the Make America Healthy Again Commission, named after a movement aligned with Health Secretary Robert F. Kennedy Jr, was released last week. It said processed food, chemicals, stress and overprescription of medications and vaccines may be factors behind chronic illness in American children, citing some 500 research studies as evidence.