After years of alarming increases in child and adult obesity and billions spent to treat related medical problems, one might think health organizations and soda companies would be on firmly opposite sides of the fence. But a new study finds that a surprising number of health groups accept soda sponsorship dollars, inadvertently helping to polish the public image of companies that actively lobby against obesity prevention efforts.

“To be honest, it was really shocking,” study co-author Michael Siegel, a professor of community health sciences at Boston University School of Public Health, told me. “I was especially surprised to see that organizations with direct missions to fight obesity are taking this money.”

Siegel said he and his co-author, Boston University medical student Daniel Aaron, had heard anecdotes about health groups taking soda company money, but quickly realized that no one had comprehensively catalogued such sponsorships. So, they decided to take on the task. To conduct their study, recently published in the American Journal of Preventive Medicine, Siegel and Aaron searched online and through databases to pinpoint records of corporate philanthropy and lobbying expenditures on public health legislation by soda companies in the U.S. between 2011 and 2015, focusing on the Coca-Cola Company and PepsiCo.

They found that during that time period, the two companies sponsored 96 health organizations and lobbied against 29 legislative efforts to reduce soda consumption and improve nutrition. Among the organizations sponsored (picking at random, click the study link above for a full list) were the American Diabetes Association, National Breast Cancer Foundation, American College of Cardiology, National Dental Association, Academy of Nutrition and Dietetics, Food Science Policy Alliance, National Physical Activity Plan, the Obesity Society and the University of Washington Center for Public Health Nutrition. (Since the study’s publication, the authors have acknowledged that they incorrectly identified the American Medical Association (AMA) as taking soda company sponsorship. The AMA did not accept soda sponsorship money during the time period studied.)

Overall, the sponsored groups included 63 public health organizations, 19 medical ones, seven health foundations, five government organizations and two food supply groups. Among the bills Coco-Cola and PepsiCo opposed during the study period were 12 soda taxes, four Supplemental Nutrition Assistance Program (SNAP) regulations and three advertising restrictions. Siegel and Aaron write:

Previous literature suggests that sponsorships of health organizations can have a nefarious impact on public health. Studies of alcohol company sponsorship and tobacco sponsorship suggest that corporate philanthropy is a marketing tool used to silence health organizations that might otherwise lobby and support public health measures against these industries. For example, Save the Children, a group that promoted soda taxes, suddenly dropped this effort in 2010 after receiving more than $5 million from the Coca-Cola Company and PepsiCo in 2009. Further, the principle of reciprocity suggests that sponsored organizations may not simply become silent, but may also support initiatives of soda companies.

Obviously, many of these health organizations would argue that soda sponsorships in no way influence their decisions or policy stances. But Siegel said it’s not as simple as that — “this isn’t a conscious effect,” he said. He noted that a significant amount of literature shows that taking money from anyone creates a subconscious effect — a bias, if you will — to which we’re all susceptible.

“It’s basic psychology that when getting money from someone, your attitude toward them will improve,” he told me. “We’re not arguing this is a conscious effect…but conflict of interest, by definition, means being influenced by financial relationships without realizing it. These conflicts of interest operate subconsciously and it’s an automatic phenomenon that can’t be avoided.”

Another problem with such sponsorships, Siegel said, is that health organizations inadvertently help soda companies boost their public image and reputation. He noted that corporate sponsorships are much more than simply philanthropy; they’re a precise function of corporate marketing. In other words, he said, such sponsorships enable soda companies to tie their brands to that of reputable health and medical organizations and, in effect, “borrow some of the good will” that such organizations have built up.

“One purpose (of sponsorships) is to divert attention away from the negative things these (soda) companies do and away from the role they play in the obesity problem,” Siegel said. “The end result of all of that is to promote their bottom line, which is soda sales.”

So, what about that old cliché about keeping your enemies close? Or the argument that such financial partnerships could help engage soda companies as serious partners in fighting the obesity epidemic, especially since their products are such significant contributors? Siegel says it doesn’t work that way. In fact, he called on health organizations to either reject soda company money outright or make it a condition of sponsorship that such companies stop campaigning against public health measures. (For example, soda companies are now working and spending to defeat a number of soda taxes on the ballot this November.)

“The way to solve public health problems is by going after industry and holding them accountable,” he said. “(Sitting down with industry) could potentially work if the ticket to getting to that table is that companies drop their opposition to public health policies. It’s simple — if you want to come to the table, stop lobbying against public health.”

Siegel told me he does envision a day when the “reputational cost” of taking soda money will simply be too high to risk. That’s what happened with big tobacco, which had long given money to mission-driven organizations to help bolster the public reputation of tobacco sellers — “ but now, tobacco companies can’t buy friends. They’re completely isolated,” Siegel noted.

Still, Siegel doesn’t blame the soda companies for their sponsorship strategies.

“We recognize that they’re in the business of selling soda and we don’t suggest that they should be in the business of improving the public’s health,” he said. “So, we’re not blaming them; if anything, we’re recognizing what a great job they’re doing in marketing their product. …What we’re really criticizing are the organizations that are enabling them and making it possible for them to use this marketing strategy. Those organizations are the ones responsible for putting an end to it.”

For a full copy of the soda sponsorship study, visit the American Journal of Preventive Medicine. For more on the state of obesity in the U.S., click here. And to read about the positive public health effects of soda taxes, read our coverage of the recent Berkeley soda tax study.

Kim Krisberg is a freelance public health writer living in Austin, Texas, and has been writing about public health for nearly 15 years.