It seems that the founding father of the saturated fat theory was a sloppy researcher. In the 1950s, Ancel Benjamin Keys studied men in the U.S., Japan and Europe and concluded that poor diet caused heart disease and other pathologies. He examined farmers living in Crete, Teicholz writes, but studied them during Lent, when they had given up meat and cheese for religious reasons. Still, Keys was apparently charismatic and convincing, and while subsequent research was mixed on the question of fats, cholesterol and disease, the whole nutritional/governmental blob had become too committed to the low-fat orthodoxy to turn back easily.
From the initial anathematizing of eggs, dairy and fat, the experts have been slowly walking it all back. First, eggs were removed from the evil list. Next, we were told dietary cholesterol actually didn't seem to be correlated with blood cholesterol at all. Then the experts explained that some fats weren't bad, and wait, that olive oil was positively good for you. And so on. Today we've nearly arrived at Allen's future. A breakfast of eggs and bacon is, according to the newest understanding, no worse for you than oatmeal. (Though sugar remains forbidden.)
Arguably, the health establishment's embrace of the wrong ideas about nutrition have made the U.S. fatter and sicker than we might otherwise have been. We've increased our consumption of carbohydrates by 25 percent since the 1970s, which may be the reason that Type 2 diabetes is reaching epidemic levels. The switch to vegetable oil from butter and lard may have increased rates of cancer and Alzheimer's disease.
The moral of this story is not to ignore science but to stay skeptical. The scientific method remains the best way yet devised to ascertain truth. But the scientific establishment is hardly immune to politics, fads, bias and self-interest. Bad science is endemic. As The Economist magazine noted in October, "half of all published research cannot be replicated ... and that may be optimistic."
Our experience with nutrition science over the past half-century should arm us with doubt about climate science, too. The point is not to ignore scientific data but to treat all studies, models and predictions with a degree of skepticism. Don't accept the argument from authority: That the entire medical establishment endorsed the war on saturated fat did not make it true.