evidence: Ex "MythBuster" Grant Imahara visits potato supplier Simplot to investigate what McDonald's french fries are actually made from. The list of ingredients might be longer than you expect. Are McDonald's french fries just potatoes or is there more to them? Are the potatoes genetically modified? What kinds of chemicals are used to fry them? Are there really 19 ingredients? [...] Even though the fries are dipped in various ingredients, fried and frozen, Imahara discovers that they do come from real potatoes. McDonald's uses a variety of potatoes, including Ranger Russet, Umatilla Russet, Russet Burbank and Shepody. And according to Neher in the video, McDonald's does not use GMO (genetically modified organism) potatoes for its french fries.