The hardest thing for an authority figure to say is, “I don’t know.”
We often ask authority figures questions they really can’t honestly answer, but the very human response is for them to make an educated guess. People tend to demand an answer of some kind from an authority figure, and if one particular expert refuses to provide an answer, people go looking for an expert who will. When you combine these tendencies with the sweeping authority of the government, you end up with the potential for major errors.
For the last 30+ years scientists, doctors, nutritionists etc. have recommended a diet low in fat as a means of preventing heart disease and cancer. The federal government has integrated this recommendation into everything from dietary guidelines to requirements for school lunches.
A study published today in the Journal of the American Medical Association looked at the association between a low-fat diet and the risk of cancer and heart attack.The study is huge, following nearly 49,000 women over a period of over 8 years. What did the study find? It found that a low-fat diet had no statistically significant effect on either cancer or heart disease.
Can you say whoops?
The study has its limitations. The fat reduction of the intervention group was considered “moderate,” so the study doesn’t tell us much about more radical restrictions on fat intake. On the other hand, the fat-intake reduction is inline with that which most people could reasonably be expected to effect, so it probably represents the results that most people in the real world could expect. Given how broad the study is, if any even near-linear relationship existed between fat intake and the studied diseases it should have showed up.
I think the low-fat-diet concept is another example of public science running ahead of hard data. The social and political dynamics overwhelm scientific discipline. People want answers and authority figures want to provide them. Authority figures don’t want to say “I don’t know” and ordinary people don’t want to hear them say it. When the government got seriously involved in nutrition in the early ’70s it became a political imperative to provide an authoritative answer. After the political and medical establishment staked its reputation on the low-fat concept, it became that much more difficult to get it reassessed.
Many people pushed the low-fat idea not because the evidence backed it but because it conformed to their social and political prejudices. Low-fat diets appeal to puritanical moralists of all stripes. Leftists love to castigate the corporate world for providing a high-fat diet to ignorant masses. Blue Staters love to mock Red Staters for their presumed high-fat diets and so on. Indeed, for every study that people thought confirmed the idea there was easily one that refuted it. The idea that the benefits of low-fat diets were well proven came from the heavy marketing of cherry-picked studies.
The parallels between the low-fat-diet concept, other instances of failures of publicly significant science such as the “energy crisis,” and the current mania concerning global warming should be obvious. In all three cases we have authorities making definitive statements for which they have no solidly confirmed data. In all three cases, powerful political factions staked out public positions based on the experts’ pronouncements. In all three cases we have a social divide where the concept plays into the prejudices of one side while affronting those of the other.
As one of the study’s authors said to the New York Times:
“But Dr. Freedman, the Berkeley statistician, said the overall lesson was clear.
“We, in the scientific community, often give strong advice based on flimsy evidence,” he said. “That’s why we have to do experiments.”
When faced with a subject like global warming, where the only real test of the concept is the passage of time, we should be doubly careful.