ARI SHAPIRO, HOST:
One food trend that will continue into 2017 is the continued push sodas and snacks with less sugar. The World Health Organization and other expert groups say high-sugar diets have helped fuel the rise in Type 2 diabetes and obesity. It's not clear how much people need to cut back on sugar. While there are specific recommendations a new battle erupted today in the pages of a prominent medical journal over the evidence behind them. NPR's Allison Aubrey reports.
ALLISON AUBREY, BYLINE: Over the last two years, new guidelines from the World Health Organization and then the U.S. government began urging Americans to consume no more than 10 percent of our daily calories from sugar. That amounts to about one sugar-sweetened soda a day. But Bradley Johnston, a researcher at the Hospital for Sick Children in Toronto who reviewed all the studies used to generate the guidelines, has concluded there's still a question about what the recommended limit should be.
BRADLEY JOHNSTON: Overall I would say that the guidelines are not trustworthy.
AUBREY: Before we go any further, I should point out that Johnston's study was funded by an industry group called the International Life Sciences Institute. It receives funding from companies including Coca-Cola, Pepsi, the candy maker Mars and McDonald's. But Johnston says he carried out his analysis independently. He says while it is wise to limit sugar, he argues there's not convincing evidence to support cutting back sugar intake to 10 percent or any other specific threshold.
JOHNSTON: There's a lot of uncertainty about the thresholds that appear in guidelines. And what's happening here is guideline panelists are making strong recommendations based on low to very low quality evidence.
AUBREY: This conclusion has drawn the ire of public health experts. Marion Nestle of New York University says this paper is an example of the industry using its weight to undermine the scientific consensus on sugar.
MARION NESTLE: It's a classic example. It's industry-funded authors saying that the dietary guidelines recommendations about sugar aren't based on science. I'm laughing because what kind of evidence do you need? Sugar is calories and no nutrients and everybody would be healthier eating less of it.
AUBREY: Eric Hentges is the executive director of the industry-funded group that sponsored the study. He refutes this accusation.
ERIC HENTGES: This is not an industry attempt to undermine the science.
AUBREY: Hentges says the paper examines the science behind the specific recommendations.
HENTGES: The purpose of the paper was to investigate specifically the quality of methods and the quality of evidence.
AUBREY: This argument does not convince Dean Schillinger. He's a physician at UC San Francisco and an advocate for diabetes prevention efforts. He's written an editorial that is published alongside the new study in the Annals of Internal Medicine.
DEAN SCHILLINGER: This is very reminiscent of what tobacco did around secondhand smoke when there was a question as to whether secondhand smoke, you know, killed people. And they called that science junk science. And it was really an attempt to undermine the scientific process and create additional doubt in the general public so that regulatory outcomes would not be in their disfavor.
AUBREY: Schillinger says when it comes to the effect of a high-sugar diet, there's no question that people should limit their sugar consumption.
SCHILLINGER: Nearly all, 97 percent of all experimental studies that examined whether eating added sugars contributes to obesity and diabetes-related outcomes show a cause and effect relationship.
AUBREY: And he says questioning the science behind the specific recommendations should not distract from the effort to nudge people to consume less sugar. Allison Aubrey, NPR News.
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