Guidelines or Guesstimates for Healthy Eating?

Release of the 2015 edition of Dietary Guidelines for Americans promises to be quite an event this month. Substantial reporting, analysis, and commentary on the subject is already dealing with the challenge of translating incomplete scientific evidence into guidelines that, in some cases, seem more like guestimates of what might be best.

The video on the right, published by the New York Times and the non-profit Retro Report, recounts the publication of the first ever dietary guidelines in 1980. The report does a good job of presenting the rush to judgment on recommending a reduction of dietary fat and cholesterol. The new guidelines will almost certainly reverse that guidance, now widely understood to be a mistake.

A classic moment in that process came when Robert Olson of St Louis University told the Senate committee behind these guidelines:

I have pleaded in my report and I will plead again orally here for more research on the problem before we make announcements to the American public.

Senator George McGovern replied:

I would only argue that senators don’t have the luxury that a research scientist does of waiting until every last shred of evidence is in.

In a Washington Post commentary, nutrition professor Marion Nestle and journalist Tamar Haspel acknowledge the difficulty of formulating guidelines, saying:

We have to rely on animal research, short-term trials and population data, all of which have serious limitations and require interpretation — and intelligent people can come to quite different opinions about what those studies mean.

But they also dismiss calls for more careful adherence to scientific evidence. They say it’s just the food industry saying “we don’t like what you said.” They commend the scientific advisors to the process for bluntly recommending that Americans eat less meat for both dietary and environmental reasons. They go on to recommend their own guidelines for better nutrition in “six easy steps.”

Environmental impact assessments have been removed from the guidelines and it’s probably a good thing. Making nutrition policy is hard enough. And it turns out that the assumption of a plant-based diet being uniformly better for the environment is not entirely correct. Scientists from Carnegie Mellon University found that wide adoption of  the proposed dietary guidelines would likely have a negative impact on the environment. Oops.

It seems that trying to change the way the entire population eats is as tricky as it is seductive. Nestle and Haspel tell us “If you go out in the world armed only with these [their own] guidelines, you’ll do great.”

We really do like their advice. But we are also mindful that such advice might not work for every American. And that is why making good dietary guidelines is so very hard.

Click here for more from the New York Times, here for the commentary by Nestle and Haspel, here for more on the environmental impact of dietary guidelines, and here for the study from Carnegie Mellon.

No Direction, photograph © Mark Dries / flickr

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January 5, 2016