"Informational cascades" undermine science in nutrition advice
Gary Taubes' new book prompted a second article in The New York Times in which NYT science writer John Tierney explains how the science underlying our dietary guidelines departed so sharply from quality science. He attributes it to the process of soliciting "expert opinion" and declares the process an "informational cascade" where an initial error is compounded and implanted as policy as successive "experts" sign-on.
"Cascades are especially common in medicine as doctors take their cues from others, leading them to overdiagnose some faddish ailments (called bandwagon diseases) and overprescribe certain treatments (like the tonsillectomies once popular for children)." Tierney recounts several of Taubes' examples, in particular that eating fat has produced an epidemic of heart disease. The original hypothesis was embraced by politicians (Sen. George McGovern (D-SD) and President Jimmy Carter's USDA activist Carol Tucker Foreman leading to the Dietary Guidelines for Americans and, eventually, today, to the Food Guide Pyramid. Unconvinced scientists were intimidated by politicians and the media; Tierney quotes economist Timur Kuran's description as "a reputational cascade, in which it becomes a career risk for dissidents to question the popular wisdom." Taubes' book includes the anecdote of an exchange of a prominent nutrition scientist responded to Sen. McGovern when McGovern asked him why he refused to accept the conclusions of "92% of the world's leading doctors." The scientist called for policy based on science, not "by anything that smacks of a Gallup poll."
