Michael Eades:

For those who don’t know the Framingham Heart Study was kicked off back in the late 1940s in Framingham, MA. under the direction of the National Heart Institute … "to identify the common factors or characteristics that contribute to CVD [heart disease] by following its development over a long period of time in a large group of participants who had not yet developed overt symptoms of CVD or suffered a heart attack or stroke." 

… this longitudinal study that is still going on today. … Researchers are monitoring diet, medication history, and a host of other parameters, and have generated God only knows how many papers using this data that has been collected over the past almost 60 years.

One of the first ideas that the researchers had was to look at how diet related to cholesterol levels and how diet related to the development of heart disease. I’ll give you the surprise ending right up front: there wasn’t any correlation.  What’s interesting about this part of the study, however, is that the researchers didn’t publish it at the conclusion of the study, so it never really saw the light of day. You’ve probably heard the old saying that doctors bury their mistakes. Well, researchers often bury outcomes they don’t expect and don’t welcome. …

These guys tried as hard as they could to show a correlation between diet and serum cholesterol and between diet and the incidence of coronary heart disease, but failed. The data conclusively demonstrated no such correlations.

Imagine my surprise then I discovered the yellowed news clipping … from the Framingham newspaper dated October 30, 1970, … Apparently, despite all the supporting evidence, Dr. Kannel, the director of the study and the guy listed as lead author, wasn’t buying into all this nonsense about there being no correlation. He felt the need to `clarify’ the already crystal clear findings.

The clipping begins:

Although there is no discernible relationship between reported diet intake and serum cholesterol levels in the Framingham Diet Study group, "it is incorrect to interpret this finding to mean that diet has no connection with blood cholesterol," Dr. William B. Kannel, director of the Framingham Heart Study has stated.

Hat tip to Seth Roberts, who sadly doesn’t seem to have learned the lesson:

"If it is impossible to find exposure-response between changes of blood cholesterol and atherosclerosis growth in 22 studies including almost 2500 individuals a relationship between the two, if any, must be trivial."  Which sounds reasonable. But an even larger number of clinical trials failed to find clear evidence that omega-3 supplementation reduces heart disease. Yet I am sure that, with a large enough dose, it does. …  I don’t know why the big clinical trials failed to point clearly in the right direction. I can think of several possibilities: …