For the last twenty years, many Americans have adjusted their diets - or felt guilty for not doing so - to include less fat, especially saturated fat, based on warnings from those supposed to know such things that dietary fat contributes to heart disease and other illnesses. Maybe not . . . John Tierney reports for The New York Times:
Alluding to his office's famous 1964 report on the perils of smoking, Dr. Koop announced that the American diet was a problem of "comparable" magnitude, chiefly because of the high-fat foods that were causing coronary heart disease and other deadly ailments.
That was a ludicrous statement, as Gary Taubes demonstrates in his new book meticulously debunking diet myths, "Good Calories, Bad Calories" (Knopf, 2007). The notion that fatty foods shorten your life began as a hypothesis based on dubious assumptions and data; when scientists tried to confirm it they failed repeatedly. The evidence against Häagen-Dazs was nothing like the evidence against Marlboros.
It may seem bizarre that a surgeon general could go so wrong. After all, wasn't it his job to express the scientific consensus? But that was the problem. Dr. Koop was expressing the consensus. He, like the architects of the federal "food pyramid" telling Americans what to eat, went wrong by listening to everyone else. He was caught in what social scientists call a cascade.
We like to think that people improve their judgment by putting their minds together, and sometimes they do.
Read the whole article at the link above. This is also the weakness of "consensus-building" generally, because of the peer pressure effect, which apparently exists at every level of academic and scientific pursuit. Add membership in a bureaucratic structure, and truth swiftly becomes a secondary goal.