Diet research conducted 40 years ago could have changed the way we eat

It was one of the largest, most rigorous experiments ever conducted on an important diet question: How do fatty foods affect our health? Yet it took more than 40 years  — that is, until today —  for a clear picture of the results to reach the public.
The fuller results appeared Tuesday in BMJ, a medical journal, featuring some never-before-published data. Collectively, the fuller results undermine the conventional wisdom regarding dietary fat that has persisted for decades and is still enshrined in influential publications such as the U.S. government's Dietary Guidelines for Americans.  But the long-belated saga of the Minnesota Coronary Experiment may also make a broader point about how science gets done: it suggests just how difficult it can be for new evidence  to see the light of day when it contradicts widely held theories.