At NPR's blog The Salt, Dan Charles has some interesting discussion on the change in the nutritional profile for Cheerios after they went "non-GMO."
Charles speculates on what caused the change. One possibility is that some vitamins these days are apparently produced with genetically modified bacteria and yeast. These microbes can reproduce quickly, and as a result they can efficiently produce vitamin B-12 or riboflavin, if they've got the right genes. It's a fascinating process that holds much promise in other applications as well.
Charles ends with what may be an interesting irony for companies who go GMO and maintain the same vitamin content: