Daniel Lubetzky

The sugar industry has a long history of shaping nutrition policy in the United States, working to mask the potential risks of consuming too much of the sweet stuff.

It wasn’t until this year, for instance, that the US Dietary Guidelines finally recommended people keep their consumption of added sugars below 10 percent of their total calorie intake — decades after health advocates began pressing for the measure. The sugar lobby had fended off this recommendation all the while.

New research, published today in JAMA Internal Medicine, shows that Big Sugar  may have done more than just advocate for favorable policies. Going back more than 50 years, the industry has been distorting scientific research by dictating what questions get asked about sugar, particularly questions around sugar’s role in promoting heart disease.

The paper focuses on a debate that first popped up in the 1950s, when the rate of heart disease started to shoot up in the United States. Scientists began searching for answers, and zeroed in on dietary saturated fat as the leading contributor. (The energy we get from food comes in three kinds of nutrients: fats, carbohydrates, and protein.)

This may not have been an accident. Through an examination of archival documents, the JAMA paper shows how a sugar trade association helped boost the hypothesis that eating too much saturated fat was the major cause of the nation’s heart problems, while creating doubt about the evidence showing that sugar could be a culprit too. Sugar increases triglycerides in the blood, which may also help harden the arteries and thicken artery walls — driving up the risk of stroke, heart attack, and heart disease.

Today, scientific consensus related to the role specific macronutrients play in the diet has shifted. Researchers have come around to the view that a person’s overall eating habits probably matter more for health than the particular percentages of carbs, fats, and proteins taken in. But they also generally agree that some kinds of fats are less damaging to health than others. (In particular, unsaturated fats appear to be better for one’s cardiovascular disease risk than saturated and trans fats.) And that too much sugar can be just as bad as too much fat for the heart.

The new JAMA paper reveals why the public may know less about the sugar-heart link than it ought to.

How the sugar industry played down the role of sugar in heart disease

Beginning in the 1950s, notes the JAMA paper, led by Cristin Kearns of UC San Francisco, a trade group called the Sugar Research Foundation was concerned about evidence showing that a low-fat diet high in sugar might raise cholesterol levels in the blood.

If sugar turned out to be a major driver of heart issues, the group surmised, that could be devastating for sugar producers.

So the Sugar Research Foundation aligned itself with leading Harvard nutrition professors, and paid them the equivalent of $48,900 (in 2016 dollars) for a two-part research review, later published in the New England Journal of Medicine, that would discredit the link between sugar and heart disease.

“[The review] concluded there was ‘no doubt’ that the only dietary intervention required to prevent coronary heart disease was to reduce dietary cholesterol and substitute polyunsaturated fat for saturated fat in the American diet,” the study authors wrote. In other words, the sugar-sponsored researchers emphasized the role saturated fat played in heart troubles, and de-emphasized the risks dietary sugar carry.

This 50-year-old incident is not ancient history

The researchers dug up this old sugar case because it still reverberates today — in both how we view sugar’s impact on the body and how science is done.

“This 50-year-old incident may seem like ancient history,” writes Marion Nestle, a New York University food policy professor, in an accompanying editorial, “but it is quite relevant, not least because it answers some questions germane to our current era. Is it really true that food companies deliberately set out to manipulate research in their favor? Yes, it is, and the practice continues.” Nestle has been documenting the instances where companies fund nutrition studies that overwhelmingly return favorable results to the industry sponsors

“Our research emphasizes that industry-funded science needs to be heavily scrutinized, and not taken at face value,” said Kearns, the lead author on the JAMA paper. “There are so many ways a study can be manipulated — from the questions that are asked, from how the information is analyzed, even to how the conclusions are described in the paper.”

In this case, the sugar industry involvement in science influenced not only the scientific enterprise but also public-health policy, and potentially, the health of millions of people. Kearns points out that the most recent World Health Organization sugar guidelines focus on reducing consumption because of sugar’s role in obesity and tooth decay — not the heart risk.

“I think [the WHO] should have also looked at the relationship between sugar and heart disease,” Kearns said. “And by having all the attention shifted off of sugar related to heart disease, we have avoided asking those specific questions.”

The Sugar Association — the trade group from which the Sugar Research Foundation in the JAMA paper evolved — continues to push back on the sugar-heart link. Most recently, the group called the American Heart Association’s recommendation that kids eat no more than 6 teaspoons of sugar a day “baffling,” arguing that it was not based on science and that added sugars can have a healthy place in children’s diets.

Updated by Julia Belluz