Its an imprecise and catchall term, but not entirely untrue. A good example of "processed food" is refined grain (non-whole-wheat bread, etc); there, various o

Its an imprecise and catchall term, but not entirely untrue. A good example of "processed food" is refined grain (non-whole-wheat bread, etc); there, various outer layers and components of each grain are milled out, leaving just the tasty starchy inner bit. Different parts of the grain will have different vitamin content, if you take only one part you may well end up with a smaller set of vitamins overall. Its not the only reason that that's bad (whole wheat is generally recommended mostly on the basis of glycemic index), but its not necessarily trivial, either.