This seems like a poor tool to keep in your logical toolbox. If some line of logic would lead to some sacred cow getting slaughtered, then that logic must be false?
In terms of the crackpot theory I'd suspect more people ate longer stored food in 1980 than today. In terms of changes that could explain a rise in a very infrequent thing I'd suspect a lot more people eat a measurable amount of transcontinental "fresh" which probably has a lot more nutritional loss than frozen for example.