About 50 years ago, the sugar industry stopped funding research that began to show something they wanted to hide: that eating lots of sugar is linked to heart disease. A new study exposes the sugar industry’s decades-old effort to stifle that critical research.

Researchers at the University of California, San Francisco, recently analyzed historical documents regarding a rat study called Project 259 that was launched in 1968. The study was funded by a sugar industry trade group called the International Sugar Research Foundation, or ISRF, and conducted by W. F. R. Pover at the University of Birmingham. When the preliminary findings from that study began to show that eating lots of sugar might be associated with heart disease, and even bladder cancer, the ISRF pulled the plug on the research. Without additional funding, the study was terminated and the results were never published, according to a study published today in PLOS Biology.

“It helped to derail this issue for quite a long time.”

Last year, based on a review of internal industry documents, the same group of UCSF researchers showed that in the 1960s, ISRF — then known as the Sugar Research Foundation — also paid Harvard scientists to obscure the relationship between sugar and heart disease, pushing them to blame saturated fats instead. Today’s study adds to the evidence that the sugar industry helped steer public discourse away from the potentially negative health effects of consuming added sugars through its research funding.

“Had [Project 259] actually been completed and published, it would have advanced the general scientific discussion about the sugar heart disease link,” says study co-author Stanton Glantz, a professor of medicine at the University of California, San Francisco. “And they prevented that from happening. It helped to derail this issue for quite a long time.”

Researching the health effects of certain foods is critical because it helps shape the federal government’s dietary guidelines, which recommend how Americans should eat in order to prevent disease. But nutrition science is sometimes influenced by industry groups that have a stake in the results: in 2015, The New York Times reported that Coca-Cola had paid scientists to distract the public from the connection between sugary drinks and obesity. Last year, The Associated Press showed that candy makers also fund bogus research: one study showed that kids who eat candy weigh less than those who don’t.

Industry-funded research often shows results that are in line with the sponsors’ interests, says Marion Nestle, a professor of nutrition, food studies, and public health at New York University, who’s writing a book on the issue. That’s also true for pharmaceutical companies, she says, which are known for suppressing research that shows unfavorable results.

“This wasn't about science. This was about marketing.”

The study in question investigated the relationship between sugars and certain blood fats called triglycerides, which increase the risk of heart disease. The preliminary results from the research, called Project 259, suggested that rats on a high-sugar diet, instead of a starch diet, had higher levels of triglycerides. The rats that ate lots of sugar also had higher levels of an enzyme called beta-glucuronidase in their urine, which at the time was thought to be potentially linked to bladder cancer, says study co-author Cristin Kearns, an assistant professor at the UCSF School of Dentistry.

The findings were described as “one of the first demonstrations of a biological difference between sucrose and starch fed rats,” according to the internal documents reviewed by the UCSF researchers. But after funding the research for 27 months, the International Sugar Research Foundation discontinued their support. So the study was never completed and the results were never published, according to the UCSF researchers. “Why would they want to fund research that would be against their interests? There’s no reason why they’d want to do that,” Nestle tells The Verge.

In a statement to The Verge, the Sugar Association — as the ISRF is known today — criticized the PLOS Biology paper, calling it not a study but a “perspective.” Project 259 was ended because it was “significantly delayed” and it was “consequently over budget,” the statement says. It adds: “Throughout its history, the Sugar Association has embraced scientific research and innovation in an attempt to learn as much as possible about sugar, diet, and health.”

It’s impossible to say whether Project 259’s early findings would have been confirmed. Today, we know that eating lots of added sugars — in sodas, sweets, and cereal for instance — increases your risk of dying of heart disease. However, there is “still no good evidence that sugar is a cause of bladder or other cancer in humans,” says Walter Willett, a professor of epidemiology and nutrition at the Harvard T. H. Chan School of Public Health, who did not take part in the research, in an email to The Verge. “This rodent research is very indirectly related to human cancer, and it would not have appreciably influenced conclusions then or now.”

Still, at the time, the preliminary results were interesting enough to warrant more research. But the sugar industry pulled the plug on the study because it didn’t like where the results were going, the UCSF researchers claim.

Nestle agrees: “This wasn't about science. This was about marketing,” she says. “If it were about science, they would have pursued it.”

Update November 22nd, 2017 09:18AM ET: The story has been updated to include a statement from the Sugar Association.