Mistaken Scientific Consensus

Thursday, October 11th, 2007 | Science |

New York Times - Diet and Fat: A Severe Case of Mistaken Consensus:

Meanwhile, there still wasn’t good evidence to warrant recommending a low-fat diet for all Americans, as the National Academy of Sciences noted in a report shortly after the U.S.D.A. guidelines were issued. But the report’s authors were promptly excoriated on Capitol Hill and in the news media for denying a danger that had already been proclaimed by the American Heart Association, the McGovern committee and the U.S.D.A.

The scientists, despite their impressive credentials, were accused of bias because some of them had done research financed by the food industry. And so the informational cascade morphed into what the economist Timur Kuran calls a reputational cascade, in which it becomes a career risk for dissidents to question the popular wisdom.

With skeptical scientists ostracized, the public debate and research agenda became dominated by the fat-is-bad school. Later the National Institutes of Health would hold a “consensus conference” that concluded there was “no doubt” that low-fat diets “will afford significant protection against coronary heart disease” for every American over the age of 2. The American Cancer Society and the surgeon general recommended a low-fat diet to prevent cancer.

But when the theories were tested in clinical trials, the evidence kept turning up negative. As Mr. Taubes notes, the most rigorous meta-analysis of the clinical trials of low-fat diets, published in 2001 by the Cochrane Collaboration, concluded that they had no significant effect on mortality.

Sounds similar to the climate change debate, doesn’t it? Except that right now temperatures are increasing, so the trend is supporting the consensus view. I know it’s beyond some people’s comprehension to think the trend won’t continue indefinitely, but it might not. Or it might continue indefinitely. I don’t know. If the temperatures dostart going back down, some people are going to have some fast talking to do.

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