Great article discussing the source and evolution of the dubious theory that butter, cheese and red meat are bad for you. Don't know why the url is so long, but for now the article is available to all and not behind the paywall:
The money quote:
"The fact is, there has never been solid evidence for the idea that these fats cause disease. We only believe this to be the case because nutrition policy has been derailed over the past half-century by a mixture of personal ambition, bad science, politics and bias."
We'e been duped. Read the whole thing.