Here’s something to ponder the next time you see a headline extolling a study that found a particular food will help you lose weight, avoid heart disease, or live longer: The company selling the product likely paid for the study; that same company also might be paying the university researcher who led the study; your tax dollars may have supplemented this company’s “research” because federal agencies regularly partner with corporations to promote foods. Finally, you’ll never discover that the “research” behind the headline is little more than marketing, because journalists rarely question these financial arrangements.

All these aspects of food are explored in Unsavory Truth: How Food Companies Skew the Science of What We Eat, a comprehensive book by Marion Nestle, emeritus professor of nutrition at New York University (pronounced nessul, and no, she has no connection to Nestlé foods). Don’t be put off by the fact that she’s an academic; Nestle writes in simple and informative language, diving into history, university politics, and failed government policies to improve people’s health.

Nestle points out that readers trying to make better food choices need to approach the media with a more skeptical eye. She advises wariness of any headline announcing that a single food, beverage, supplement, food product, or ingredient causes or reduces the risk for obesity, heart disease, type 2 diabetes, or cancer. The studies behind these stories are often developed by a company’s marketing department.

In some cases, research is designed to be actively deceptive. Coca-Cola was recently caught funding academics to publish studies that shifted the debate on obesity away from the consumption of sodas to lack of exercise. A study of media reports generated by these studies found that journalists helped to keep this money hidden in at least 30 news articles that failed to mention the scientists’ financial ties to Coca-Cola.

Nestle says that journalists have been sloppy in disclosing the funding behind research and the financial ties of their sources, and at times even help promote the industry’s agenda. (One headline she cites, from Slate: “So what if the sugar industry funds research? Science is science.” Despite a large body of research showing that funding does indeed bias results, the reporter on this story attempted to argue to the contrary. The article was then promoted on Twitter by a professional society with financial ties to industry and which regularly promotes food company interests.)

Ignoring the journalistic rule to “follow the money” means that reporters are failing to inform their readers and the public. “Unless reporters take on this challenge,” she writes, “you are on your own to figure out how skeptical you need to be about news reports or expert advice.”

Tonic: You document how much of food “research” is really just marketing. I was struck by studies sponsored by blueberry and pomegranate companies that found these two fruits may reduce the risk of erectile dysfunction. It’s 2018: Where are the studies finding fruits help women have better sex and more orgasms?

Marion Nestle: I want that study! We love studies that tell us what we want to hear. The single most obvious observation of industry funding is that research results and opinions almost invariably favor the sponsor’s interests. If you are the producer of a specific kind of fruit, you want a larger market share for what you are selling, never mind how improbable or trivial the science. I’m totally for eating more fruit, but does it really matter whether you are eating peaches, kiwis, or apples? The key to healthy diets is variety, and all fruits have plenty of nutritional value and taste to contribute.

You start by examining the documented history of corruption in pharmaceuticals. For decades, companies have been using university professors and their research to push drugs that may be either dangerous or don’t work. We are in the midst of an opioid epidemic and physicians helped cause it. These exact same systems seem to exist in food and nutrition departments.

I see plenty of parallels. The big difference? There is vastly, overwhelmingly, more research on the effects of drug-industry funding than there is on food or beverage company efforts to influence research. The first published study of food or beverage influence was from 2003, and I only found 11 studies in total. Drug-industry funding? Decades of research, thousands of studies, and libraries of books. Why is concern about food-industry funding so recent and so rare? We have to eat to live and we think of these companies as providing a service. They are not social service companies; they are businesses whose primary mission is to generate profits for stockholders.

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Explain what a financial conflict of interest is in science.

Let’s say your research is funded by Coca-Cola or you consult for that company. You have just been appointed to an advisory committee that will be making recommendations about whether sugary drinks should be allowed to be sold in schools. Do you vote for sugary drinks or public health in that situation? One huge problem is that industry influence largely occurs at an unconscious level. You don’t think financial ties will have any influence. But much evidence says they will.

Your book explains that we often get bad advice from the media who run stories about rotten studies; many nutrition organizations are co-opted by companies, as are government agencies. And our physicians don't really have training in nutrition and are influenced by this PR like everyone. But what does distorted science mean for us?

Conflicted research distorts the research agenda, confuses the public about what to eat, muddies dietary advice, and reduces public trust in science—none of these are good for the health of people or society.

I wrote a piece about chemical companies corrupting safety policies and pointed out that some journals regularly publish junk by industry consultants. During editing, my editor asked, “Well what about peer review? These studies are peer-reviewed.” I had to explain to her that peer review is just glorified editing. I feel like this is the norm: People see “science” and they think that means it must be true and can’t be questioned.

Peer reviewers and editors need to pay much more attention to who pays for studies. I routinely do peer reviews for nutrition, medical, science, and public health journals. When I see an industry-funded study with a research design and result clearly designed for marketing purposes, I point it out and vote do not publish. I wish more peer reviewers would do that. Editors also should reject studies that are aimed at marketing, not science. All too many editors have their own sets of financial ties to companies, alas.

We also see this with scientists. They deny that money can cause influence, yet we have all this science telling us that it does. Why do scientists deny this science?

I’m guessing they don’t know it exists. They haven’t read the literature in psychology and behavioral economics. Or maybe they have, and don’t think it applies to them. I quote scientists who accept research funds from food companies as arguing that science is science and that’s all that counts. Here too, there is research—this time saying that industry influence usually occurs in the design of the research question or interpretation of results, not in how well the science is performed.

Pointing out industry influence can cause problems for the person pointing the finger. You write that you have had articles rejected and have irritated colleagues. What else has happened to you for commenting on financial influence in science?

Not much really, except for nastiness on social media and occasional legal threats that usually don’t go anywhere. I try as hard as I can to be precise in my writing and to back up my statements with reliable references (this book has more than 600). Also, I am hugely privileged in having been tenured at a university that supported my work and doing work that did not require external funding. I would not advise untenured faculty to do anything likely to generate this level of controversy.

You had to shut down comments on your Food Politics blog when you were attacked with hundreds of comments by Monsanto’s Twitter trolls. And the American Council on Science and Health (ACSH) has a denigrating profile of you written by a guy who works for the Genetic Literacy Project, which is a website owned by a PR company. Both of these groups are fronts for the agrochemical industry. Why didn’t you write more about corporate front groups?

I’d already written about those front groups in my previous books—the ACSH in Food Politics and Soda Politics, and GMO groups in Safe Food. I decided not to talk about anything related to production agriculture—GMOs, input chemicals, and organics—but to stick to issues related to food consumption. Pretty much the only front group I discuss is ILSI (the International Life Sciences Institute). When I finished writing the book, I was amazed by how often I mentioned ILSI involvement. It positions itself as an independent think tank on food issues but it is funded by hundreds of food companies and promotes their interests all over the world.

Switching to some good news, you emphasized the importance of investigative journalists who file public records requests to uncover hidden ties between academics and corporations. But we don’t have enough reporters like this. What are your thoughts?

I relied heavily on the work of AP reporter Candice Choi and Anahad O’Connor at the New York Times, who filed open records requests. The emails they collected showed how food companies and trade associations actually exert influence. Otherwise we would never know how they try to influence reporters by giving them information, inviting them to sponsored meetings, and cozying up to them in other ways. I also relied on the work of other reporters who expose corporate influence on research and practice.

I’ve documented several instances of reporters attending junkets sponsored by Coca-Cola and the agrochemical industry. Do you think the reporting is getting worse as journalism goes through this downturn in the last decade?

Reporters are human and humans tend to think that corporate connections do not influence their opinions or work—despite vast amounts of research to the contrary. Fewer and fewer reporters have full-time paid positions with news outlets and more and more are reliant on freelancing and getting paid as best they can. This makes them vulnerable to conflicted relationships, especially if they do not recognize how they are conflicted.

I’m struck by all the food advice out there—walls of books at stores, tons of magazine articles, and new stories appearing every day. Yet most experts offer pretty simple advice such as: Avoid processed food, cook your own meals, eat more fruits and vegetables, and get some exercise a few times a week. It’s all pretty obvious, but I think people still seek a personal trainer at a top gym and some special diet plan with organic, probiotic smoothies.

I love quoting Michael Pollan: “Eat food. Not too much. Mostly plants.” Really, that takes care of dietary advice. But putting this advice into practice is difficult for a host of reasons, not least food marketing. I am always amazed by how food marketing is so often ignored in talking about food choice—as if it has no influence. An advertising executive once told me that for marketing to succeed, it had to slip below the radar of conscious thought. Food companies are great at marketing to passions for music or sports or, for that matter, influencing research.

You end your book with, “As citizens, we need and deserve healthier, more sustainable, and more ethical food systems. If we do not demand them, who will?” Do you think people will do this, or are we just running in place?

I am in the fortunate position of teaching young people passionately interested in food issues and wanting to dedicate their lives to creating food systems that promote the health of people and the planet. Food choices matter. As I love to put it, every time you buy a food, drink, or meal, you are voting with your fork for the kind of food system you want. These days, it is even more important to understand the role of politics in food choice and to vote with your vote. I hope my book will inspire both kinds of voting.

This interview has been edited for length and clarity.

Correction 11/26/18: One question above has been rephrased for accuracy.