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The Sugar Industry Killed a Study 50 Years Ago That Suggested a Link to Cancer

“Their goal was to derail the scientific conversation on these issues.”
Ruth Bushi / EyeEm

Nearly 50 years ago, researchers began a study examining how a high-sugar diet affected gut microbes in rats. The study was funded by a sugar industry trade group and, after preliminary results linked the high-sugar diet to heart disease and bladder cancer, the group terminated the project. The study was never completed; its early results were never published but they were re-discovered in archives only recently.


That’s according to a new paper published in the open-access journal PLOS Biology. Drawing on internal documents from the International Sugar Research Foundation (ISRF), authors Cristin Kearns, Dorie Apollonio, and Stanton Glantz of the University of California San Francisco describe a rat study known as Project 259. For the project, a researcher named W.R.F. Pover of the University of Birmingham planned to compare two groups of rats: one group fed a diet high in sucrose, or table sugar, and another group that consumed starch instead.

At the time, scientists disagreed over whether sugar could elevate triglycerides, a type of fat found in the blood; high levels of triglycerides are associated with increased risk of heart disease. The early results from Project 259, as the ISRF noted in an internal summary, provided "one of the first demonstrations of a biological difference between sucrose and starch fed rats." It suggested that a high-sugar diet could have measurable effects, and not good ones. In particular, suggested that yes, a diet high in sugar can elevate triglycerides, increasing the risk of heart disease.

Discounting any link between sugar and heart disease was an important goal for the sugar industry at the time: Kearns and her colleagues have already used documents from the ISRF’s predecessor, the Sugar Research Foundation, to show how the organization marshalled industry-sponsored studies to shift the blame for heart disease from sugar to fat in 1967. A year later, Project 259 began.


When the ISRF received the triglycerides results, it cut the project’s funding, leaving the study unfinished and its findings unpublished. The authors of the new paper argue that killing the study served the ISRF’s larger purpose of keeping sugar untainted by links to cardiovascular disease.

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It also meant that a troubling finding of the rat study—the link between sugar and bladder cancer—remained unknown. It’s a link that should be re-examined today, the authors argue. Just last year, the Sugar Association, the current name of the industry’s trade group, said that "no credible link between ingested sugars and cancer has been established."

For the paper’s authors, Project 259 is a small part of a larger pattern. “Their goal was to derail the scientific conversation on these issues—and they did a pretty good job of it,” Stanton Glantz, professor at UCSF’s Philip R. Lee Institute for Health Policy Studies, and a co-author, told Tonic.

The paper also draws attention to the larger problem of industry-sponsored research. “I think the most important point of this story is that the sugar industry refused to pay for research that ran the risk of coming out unfavorably,” Marion Nestle, the Paulette Goddard Professor of Nutrition, Food Studies, and Public Health, emerita, at New York University, told Tonic via email. “This is common practice in research funded by the drug industry but this is the first documented instance of which I am aware for food.” (Nestle wrote an editorial accompanying the UCSF team’s previous analysis of the internal documents, but was not involved in either study.)

When reached for comment, the Sugar Association responded with a statement saying in part, that “the study in question ended for three reasons, none of which involved potential research findings: the study was significantly delayed; it was consequently over budget; and the delay overlapped with an organizational restructuring with the Sugar Research Foundation becoming a new entity, the International Sugar Research Foundation. There were plans to continue the study with funding from the British Nutrition Foundation, but, for reasons unbeknown to us, this did not occur.”

Sugar Association president and CEO Courtney Gaine also responded via email, writing, “There is still no credible link or direct relationship found between sugar and cancer. The research they are referencing was conducted nearly half a century ago and was never finished, so any findings could only be considered preliminary and exploratory at best.”

Glantz acknowledges Project 259’s delay and small budget overrun, but counters that its findings are now considered preliminary precisely because funding was cut, which prevented researchers from finishing the study. He and Kearns emphasize that they’ve made no claims about sugar causing cancer, rather they believe the link demands further research. After almost five decades, it’s not too late to follow up.

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