A prominent medical journal on Monday published a scathing attack on global health advice to eat less sugar. Warnings to cut sugar, the study argued, are based on weak evidence and can’t be trusted.
But the review, published in the Annals of Internal Medicine, quickly elicited sharp criticism from public health experts because the authors have ties to the food and sugar industries.
The review was paid for by the International Life Sciences Institute, a Washington, D.C.-based scientific group funded by multinational food and agrochemical companies including Coca-Cola, Hershey’s, General Mills, Kraft Foods, Kellogg’s and Monsanto. One of the authors is a member of the scientific advisory board of Tate & Lyle, one of the world’s largest suppliers of high-fructose corn syrup.
Critics say the medical journal review is the latest in a series of efforts by the food industry to shape global nutrition advice by supporting prominent academics who question the role of junk food and sugary drinks in causing obesity, Type 2 diabetes and other health problems. A report in September revealed that those efforts began in the 1960s when the sugar industry paid scientists to cast doubt on the link between sugar and heart disease and promote saturated fat as the culprit instead. More recently an article in The New York Times found that Coca-Cola had been funding scientists who played down the connection between sugary drinks and obesity. And The Associated Press reported in June that food companies paid for studies that claimed candy-eating children weigh less.Some experts said the Annals review appears to be an attempt by the industry to undermine sugar guidelines from the World Health Organization and other health groups that urge children and adults to eat fewer foods with added sugar, such as soft drinks, candy and sweetened cereals. The paper, they say, is reminiscent of tactics once used by the tobacco industry, which for decades enlisted scientists to become “merchants of doubt” about the health hazards of smoking.
“This comes right out of the tobacco industry’s playbook: cast doubt on the science,” said Marion Nestle, a professor of nutrition, food studies and public health at New York University who studies conflicts of interest in nutrition research. “This is a classic example of how industry funding biases opinion. It’s shameful.”
But the scientists behind the paper said more scrutiny of sugar guidelines is needed. The researchers reviewed guidelines issued by the W.H.O. and eight other agencies around the world and said the case against sugar is based on "low-quality” evidence.
“The conclusion of our paper is a very simple one,” said Bradley C. Johnston, a professor of clinical epidemiology at the University of Toronto and McMaster University and the lead author of the new paper. “We hope that the results from this review can be used to promote improvement in the development of trustworthy guidelines on sugar intake.”
Dr. Johnston said he recognized that his paper would be criticized because of its ties to industry funding. But he said he hoped people would not “throw the baby out with the bathwater” by dismissing the conclusion that sugar guidelines should be developed with greater rigor. He also emphasized that he was not suggesting that people eat more sugar. The review article, he said, questions specific recommendations about sugar, but “should not be used to justify higher intake of sugary foods and beverages.”
The industry-funded review comes as health authorities around the world are increasingly taking steps to curb the amount of sugar people consume. Last year the W.H.O. said that adults and children should restrict their intake of sugar from most foods – other than fruit, vegetables and milk – to 10 percent of their daily calories. The W.H.O. said it relied on the latest scientific evidence, which showed that adults and children consuming a lot of sugar were more likely to gain weight or become obese. In the United States, the Food and Drug Administration has promised new labeling rules that require food companies to disclose added sugars. Recently, six local governments approved taxes on soft drinks. And in Britain, the health agency Public Health England called for strict limits on daily sugar intake.
The Annals review gave poor ratings to all of the sugar guidelines it evaluated, saying the quality of the evidence they were based on was “low to very low.” It said the guidelines were generally not transparent about how the recommendations were reached, and that most of them failed to include disclosures about potential conflicts of interest among their authors.
Barry Popkin, a professor of nutrition at the University of North Carolina at Chapel Hill, said he was stunned that the paper was even published at all because its authors “ignored the hundreds of randomized controlled trials” that have documented the harms of sugar.
“They ignored the real data, created false scores, and somehow got through a peer review system that I cannot understand,” he said. “It is quite astounding.”
Dr. Christine Laine, editor in chief of the Annals of Internal Medicine, defended the journal’s decision to publish the industry-funded review. She said in an interview that the journal makes decisions based on the quality of the research, not the source of funding.
“We thought that this was something that our readers would be interested in, and we thought the methods of the systematic review were high quality,” Dr. Laine said. “We decided to go ahead and publish it despite the fact that we’re completely aware that the funding source has a relationship with the food and beverage industry.”
Dr. Dean Schillinger, chief of the University of California, San Francisco, division of general internal medicine at San Francisco General Hospital, said it was fine to question the quality of nutrition guidelines and to hold them to high standards, but that in this case the researchers and their financial backers had an obvious agenda.
“They’re hijacking the scientific process in a disingenuous way to sow doubt and jeopardize public health,” said Dr. Schillinger.
Dr. Schillinger, who co-authored an accompanying editorial criticizing the methodology of the Annals review, disclosed that he had served as a paid expert for the city of San Francisco last year when it was sued by the beverage industry for requiring warning labels on soft drink advertisements.
Other experts agreed with the industry study’s point that more rigor is needed in issuing nutrition guidelines, but added that the current guidelines should go much farther.
Dariush Mozaffarian, a cardiologist and the dean of the Friedman School of Nutrition Science and Policy at Tufts University who has served as a peer reviewer on the sugar guidelines issued by the World Health Organization and the American Heart Association, said there was very strong scientific evidence that sugar promotes adverse health effects like weight gain and Type 2 diabetes.
But, he said, most guidelines that urge people to limit sugar say nothing about reducing refined starches, even though studies suggest that both are equally harmful.
“It’s unfair to single out sugar and not starch,” he said. “I would like to see recommendations to limit both sugar and starch. But that’s half the calories in the food supply.”
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