The sugar industry's funding and role were not disclosed when the article was published by the New England Journal of Medicine. The journal, which did not require such disclosures at the time, began requesting author disclosures in 1984.
In an editorial published Monday that accompanied the sugar industry analysis, New York University professor of nutrition Marion Nestle noted that for decades following the study, scientists and health officials focused on reducing saturated fat, not sugar, to prevent heart disease.
While scientists are still working to understand links between diet and heart disease, concern has shifted in recent years to sugar and carbohydrates, and away from fat, Nestle said.
A committee advising the federal government on dietary guidelines says the available evidence shows "no appreciable relationship" between the dietary cholesterol and heart disease, although it still recommended limiting saturated fats.
The American Heart Association cites a study published in 2014 in saying that too much added sugar can increase risk of heart disease, though the authors of that study says the biological reasons for the link are not completely understood.
The findings published Monday are part of an ongoing project by a former dentist, Cristin Kearns, to reveal the sugar industry's decades-long efforts to counter science linking sugar with negative health effects, including diabetes. The latest work, published in the journal JAMA Internal Medicine, is based primarily on 31 pages of correspondence between the sugar group and one of the Harvard researchers who authored the review.
In a statement, the Sugar Association said it "should have exercised greater transparency in all of its research activities," but that funding disclosures were not the norm when the review was published. The group also questioned Kearns' "continued attempts to reframe historical occurrences" to play into the current public sentiment against sugar.
The Sugar Association said it was a "disservice" that industry-funded research in general is considered "tainted."
Companies including Coca-Cola Co. and Kellogg Co. as well as groups for agricultural products like beef and blueberries regularly fund studies that become a part of scientific literature, are cited by other researchers, and are touted in press releases.
Companies say they adhere to scientific standards, and many researchers feel that industry funding is critical to advancing science given the growing competition for government funds. But critics say such studies are often thinly veiled marketing that undermine efforts to improve public health.
"Food company sponsorship, whether or not intentionally manipulative, undermines public trust in nutrition science, contributes to public confusion about what to eat," wrote Nestle, a longtime critic of industry funding of science.
The authors of the analysis note they were unable to interview key actors quoted in the documents because they are no longer alive. They also note there is no direct evidence the sugar industry wrote or changed the manuscript, that the documents provide a limited window into the activities of the sugar industry group and that the roles of other industries and nutrition leaders in shaping the discussion about heart disease were not studied.
Nevertheless, they say the documents underscore why policy makers should consider giving less weight to industry-funded studies. Although funding disclosures are now common practice in the scientific community, the role sponsors play behind the scenes is still not always clear.
In June, the Associated Press reported on a study funded by the candy industry's trade group that found children who eat candy tend to weigh less than those who don't. The National Confectioners Association, which touted the findings in a press release, provided feedback to the authors on a draft even though a disclosure said it had no role in the paper. The association said its suggestions didn't alter the findings.
In November, the AP also reported on emails showing Coca-Cola was instrumental in creating a nonprofit that said its mission was to fight obesity, even though the group publicly said the soda maker had "no input" into its activities. A document circulated at Coke said the group would counter the "shrill rhetoric" of "public health extremists."
Coca-Cola subsequently conceded that it had not been transparent, and the group later disbanded.