The Evidence

Adequate Evidence for Dietary Guidelines

Today, as the 2015 edition of Dietary Guidelines for Americans is moving toward completion, the Mayo Clinic Proceedings has published a fundamental debate about adequate evidence for dietary guidelines and nutrition research. In a review of the data on American dietary behavior, Edward Archer, Gregory Pavela, and Carl J. Lavie conclude that it is “pseudoscientific and inadmissible in scientific research.”

In a brief rebuttal, Brenda Davy and Paul Estabrooks reject the analysis of Archer et al as “scientific doublespeak.”

The heart of this problem is self-reported dietary data. To recommend what Americans should eat, the Dietary Guidelines Advisory Committee starts with an understanding of what they currently eat. The problem is that it’s based on self-reports and people systematically misremember what they eat. People tend to forget some of the bad stuff they eat, and remember themselves as making choices that they wish they would have made. Memory is fallible. People are constantly judged by what they eat (Geico captured this well in an entertaining commercial, below). Thus, memory-based self-reports of eating behavior are so unreliable that Archer and others believe them to be useless.

Davy and Estabrooks argue that the limitations of dietary self-reports are “well-recognized and acknowledged” and that measures of behavior matter are essential for constructing dietary guidelines. Their bottom line seems to be that self-reports are “the only comprehensive source of information on the food and nutrient intake of the US population” — so we’re stuck with them.

Let’s face it. Many of us are hooked on bad data from self-reports. And as such, we get cranky when our fix is at risk. So intemperate remarks about “scientific doublespeak” are understandable.

Regardless, it’s time to kick the bad-data habit.

Click here for the analysis by Archer et al. Click here for the rebuttal by Davy and Estabrooks. Click here for more on the subject from ConscienHealth.

The Evidence, photograph © BG / flickr

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