This was actually one of the first things I learned in my sociology class at medical school. The lecturer used cancer as the example, and had literally hundreds of news articles with different types of food that they say at different times both cause and prevent cancer. It's been happening for a long time (I went to school 2008-2012, and she filled a 2 hour lecture with slides of this shit). Edit - should have mentioned, it was my first big red pill moment.