My attitude toward nutrition science is to be skeptical of everything. I am of the generation that lived through the SnackWells fat-free cookie craze (demand was so high at one point that there was a problem with continuous understocking). A friend who is a professor of biology once admitted to me that part of him feels somewhat bad for anti-vaccination believers, because when it comes to nutrition he and many of his colleagues take a very jaundiced view of any orthodoxy. The surfeit of observational studies combined with the huge revenues at stake mean that skepticism is warranted.

This puts the public, and those who serve them in a peculiar position. Last year I recall going to a restaurant where some of the menu items were labeled as “low cholesterol, heart healthy.” I told our server that there is no evidence that dietary cholesterol has any effect on serum levels in your body. But the overhang of nutritional orthodoxy persists, and the American Heart Associations prominence and tendency to be a lagging indictor of the science is going to cast a pall over “public awareness” for decades.

Now researchers are going back to the original studies which supported modern orthodoxy, and finding results that are surprising. Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73). Here is the conclusion:

Available evidence from randomized controlled trials shows that replacement of saturated fat in the diet with linoleic acid effectively lowers serum cholesterol but does not support the hypothesis that this translates to a lower risk of death from coronary heart disease or all causes. Findings from the Minnesota Coronary Experiment add to growing evidence that incomplete publication has contributed to overestimation of the benefits of replacing saturated fat with vegetable oils rich in linoleic acid.

The whole story is told over at Scientific American.