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In 2016, a Washington-based lobby group published a scientific review which concluded that evidence in favor of guidelines recommending limits on added dietary sugar was “low quality,” and did not “meet criteria for trustworthy recommendations.” This was a group funded by multinational food and agrochemical companies from Coca-Cola to Monsanto to the captains of corn syrup, accused of “hijacking the scientific process in a disingenuous way to sow doubt and jeopardize public health.” But exactly how did they get away with it?

Here’s their paper, questioning the scientific basis of guideline recommendations on sugar intake. Using the “GRADE” approach, they concluded that the overall quality of evidence to support such recommendations was low to very low. GRADE stands for the Grading of Recommendations Assessment, Development and Evaluation initiative, which was developed to make clinical guidelines more evidence-based, and thank heavens for that. Clinical guidelines, like which drug to give to whom, used to be developed by something like the GOBSAT method (just some Good Old Boys Sitting Around a Table).

Under GRADE, high-quality evidence appears to be derived exclusively from randomized trials. This is not surprising, given that the GRADE process was designed for drugs, and, of course, you want your drugs put to the test. Like, remember the Premarin story, where for a decade, organizations recommended that clinicians encourage postmenopausal women to use hormone replacement therapy, because women who were taking it appeared to have fewer heart attacks. But when put to the test, randomized controlled trials instead showed the opposite. So, we definitely want drugs put through randomized double-blind, placebo-controlled trials, where people are randomized to take the drug or unknowingly take a placebo instead, and no one knows who’s in which group until the code is broken at the end, and you see how well the two groups did compared to each other.

Everyone agrees that randomized controlled trials are enormously valuable in many areas of medical research, such as the testing of drugs. But wait a second, how do you do that with diet? There’s no such thing as a placebo diet. How can you randomize people to different diets, but somehow hide from them which diets they’re following? People tend to notice what they put in their own mouths. And randomized controlled trials are so expensive they typically last for only weeks or months. But it takes most cancers decades to develop; so, it’s nearly impossible to see if different diets prevent or cause cancer that way. To see if smoking causes cancer, you can follow large cohorts of smokers and nonsmokers out for decades to see who gets cancer and who doesn’t. But it’s not like you can randomize people to smoke or not smoke for decades. When studying lifestyle interventions, you often just can’t do randomized controlled trials. And even if you could, it might not be ethical.

Take crib death, for example––sudden infant death syndrome (SIDS). A pivotal study studying the habits of infants who died discovered that sleeping on their stomachs was a risk factor; so, we started educating parents “face up to wake up,” and the SIDS rates dropped. What more do we need? Would it even be ethical to randomize thousands of babies to sleep on their backs or fronts and count up the deaths at this point? You can get sufficient evidence to make lifestyle recommendations that save lives without randomized controlled trials.

Critical questions, like “What dietary pattern produces the best health outcomes over a lifetime?” simply can’t be answered with randomized controlled trials. You can’t randomize people to different lifetime diets and expect them to stick to them; so, we need to compile an amalgamation of evidence from other study designs.

The lack of evidence from randomized controlled trials has become a common argumentation strategy for criticizing nutrition recommendations. Similar claims were made by the tobacco industry in its attempt to discredit evidence on the harms of tobacco. Case in point: the so-called “sound science” campaign carried out by Philip Morris. This is all straight out of the tobacco industry playbook.

Philip Morris used public relations firms and lawyers to develop a “sound science” program that involved recruiting other industries and issues to obscure the tobacco industry’s role. They tried to enshrine “good epidemiological practices” that would make it impossible to conclude that secondhand smoke—and thus other environmental toxins—caused diseases.

“Public health professionals need to be aware that the ’sound science’ movement is not an indigenous effort from within the profession to improve the quality of scientific discourse, but rather reflects sophisticated public relations campaigns controlled by industry executives and lawyers whose aim is to manipulate the standards of scientific proof to serve the corporate interests of their clients.” And not just tobacco clients, but they hope to expand to the food, plastics, and chemical industries. Philip Morris went beyond just “creating doubt” and “controversy” about the scientific evidence, to attempting to change the scientific standards of proof. But randomized controlled trials aren’t the only source of good evidence. As Sir Bradford Hill himself said, who pioneered the randomized controlled trial: “Any belief that the controlled trial is the only way to go would mean not that the pendulum had swung too far but that it had come right off its hook.”

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