In a recent post, I had a footnote that claimed purified corn oil is basically identical regardless of whether or not it came from GM corn or not. I’d read up on it months ago and didn’t feel it necessary to provide explicit links since it’s not exactly a hard case to demonstrate. But it seems useful to have some of those links sitting around.
First, purified oils in general contain no detectable proteins. Further, the EPA notes, that Bt proteins are broken down readily by normal food processing (e.g. cooking) and in the digestive system. Since the major modifications in transgenic corns currently only add or modify expression of proteins (e.g. production of Cry proteins), it seems unlikely that if processing removes these proteins, a GM corn product could be different from its non-GM counterpart.
However, there is a remaining question: did modifying corn to add traits to produce Bt toxins or to tolerate herbicides change the composition of the produced plant other than the desired proteins? Various published research I’ve found suggests the answer is that there are no differences: Bt corn composition, Bt corn in pig nutrition, and review of nutrition studies.
While this is a cursory look, more competent people than I have looked into it and found no significant differences in GM and non-GM foods. Further, purified substances like corn oil are chemically the same because they are refined to the point that the actual differences are removed. There is little evidence to suggest that current GM corn oils are different than non-GM corn oils.