What percent of Amercian's even get those things you list though a non-fast food diet? Eating out of a box or a microwave like a large number of people do isn't any better. Hot dogs, mac & cheese, cold cut sandwiches, PB&J, ect. They have none of the items you list but people eat them as a staple of their diet day in and day out.
Edit: Seems they put folic acid in cereal now
I'd say folic acid and lutein, and perhaps omega 3 fats are the things they wouldn't get.
A simple cereal would fix the iron and B vitamins, zinc and potassium problem.
Heated tomato paste would give you lycopene.
Just because many Americans don't get enough folic acid doesn't mean not getting it is healthy. Health is not how fat you are (well that can be one of many factors).
http://www.wholehealthmd.com/refshelf/substances_view/1,1525,887,00.html
A moderate folic acid deficiency exhibits no symptoms, but it does increase vulnerability to heart disease. In women, a deficiency can increase the risk of bearing a child with birth defects. In rare cases, people can develop a severe deficiency, which may lead to a serious form of anemia called megaloblastic anemia, and to chronic diarrhea, a sore red tongue, and poor growth in children. Those most susceptible to a severe deficiency are alcoholics, people on certain types of medications (for epilepsy or cancer), and people with disorders that affect their ability to absorb nutrients, such as Crohn's disease or celiac sprue.
So you can live without getting enough. But it does damage. This is not healthy.
http://my.webmd.com/content/Article/90/100860.htm
http://www.aboutkidshealth.ca/ofhc/news/Other/4260.asp
Lacking omega 3 fats does brain damage (especially lack of DHA during pregnancy, if the damage is done from that diet can only help so much). Again, not healthy.
